Variadic function: Difference between revisions
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{{task|Basic language learning}}[[Category:Functions and subroutines]]
;Task:
Create a function which takes in a variable number of arguments and prints each one on its own line.
Also show, if possible in your language, how to call the function on a list of arguments constructed at runtime.
Functions of this type are also known as [[wp:Variadic_function|Variadic Functions]].
;Related task:
* [[Call a function]]
<br><br>
=={{header|ACL2}}==
<syntaxhighlight lang="lisp">(defun print-all-fn (xs)
(if (endp xs)
nil
(prog2$ (cw "~x0~%" (first xs))
(print-all-fn (rest xs)))))
(defmacro print-all (&rest args)
`(print-all-fn (quote ,args)))</syntaxhighlight>
=={{header|ActionScript}}==
<
{
for (var i:int = 0; i < args.length; i++)
trace(args[i]);
}</
=={{header|Ada}}==
Ada doesn't have variadic functions. But you can mimic the behavior by defining a function with an unconstrained array as its parameter, i.e., an array whose length is determined at run time.
<syntaxhighlight lang="ada">with Ada.Strings.Unbounded, Ada.Text_IO;
procedure Variadic is
subtype U_String is Ada.Strings.Unbounded.Unbounded_String;
use type U_String;
function "+"(S: String) return U_String
renames Ada.Strings.Unbounded.To_Unbounded_String;
function "-"(U: U_String) return String
renames Ada.Strings.Unbounded.To_String;
type Variadic_Array is array(Positive range <>) of U_String;
procedure Print_Line(Params: Variadic_Array) is
begin
for I in Params'Range loop
Ada.Text_IO.Put(-Params(I));
if I < Params'Last then
Ada.Text_IO.Put(" ");
end if;
end loop;
Ada.Text_IO.New_Line;
end Print_Line;
begin
Print_Line((+"Mary", +"had", +"a", +"little", +"lamb.")); -- print five strings
Print_Line((1 => +"Rosetta Code is cooool!")); -- print one string
end;</syntaxhighlight>
Output:<pre>Mary had a little lamb.
Rosetta Code is cooool!</pre>
=={{header|Aime}}==
Printing strings:
<syntaxhighlight lang="aime">void
f(...)
{
integer i;
i = 0;
while (i < count()) {
o_text($i);
o_byte('\n');
i += 1;
}
}
integer
main(void)
{
f("Mary", "had", "a", "little", "lamb");
return 0;
}</syntaxhighlight>
Printing data of assorted types:
<syntaxhighlight lang="aime">void
output_date(date d)
{
o_form("~%//f2/%//f2/", d.year, d.y_month, d.m_day);
}
void
g(...)
{
integer i;
record r;
r["integer"] = o_integer;
r["real"] = o_;
r["text"] = o_text;
r["date"] = output_date;
i = 0;
while (i < count()) {
r[__type($i)]($i);
o_byte('\n');
i += 1;
}
}
integer
main(void)
{
g("X.1", 707, .5, date().now);
return 0;
}</syntaxhighlight>
=={{header|ALGOL 68}}==
Line 14 ⟶ 130:
allows the passing of strongly typed variable arguments to procedures.
{{works with|ALGOL 68|
{{works with|ALGOL 68G|Any - tested with release
{{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release [http://sourceforge.net/projects/algol68/files/algol68toc/algol68toc-1.8.8d/algol68toc-1.8-8d.fc9.i386.rpm/download 1.8-8d]}}
<
MODE STRINT = UNION(STRING, INT, PROC(REF FILE)VOID, VOID);
Line 35 ⟶ 151:
print strint(("Mary","had",1,"little",EMPTY,new line))
)</
Output:
<pre>
Mary had 1 little *
</pre>
Also note that '''empty''' (of type '''void''') can be used to indicate missing or optional arguments.
For another example see [[Average/Simple_moving_average#ALGOL_68|Average/Simple moving average]]. This example is closer to the keyword arguments found in python.
=={{header|AppleScript}}==
{{works with|OS X Yosemite onwards|(10.10+) for the use of NSDictionary with record arguments}}
AppleScript handlers have no internal access to an argument vector, but we can use AppleScript's Patterned Parameters, in the form of lists of arbitrary length for variadic positional parameters, or records for variadic named parameters.
<syntaxhighlight lang="applescript">use framework "Foundation"
-- positionalArgs :: [a] -> String
on positionalArgs(xs)
-- follow each argument with a line feed
map(my putStrLn, xs) as string
end positionalArgs
-- namedArgs :: Record -> String
on namedArgs(rec)
script showKVpair
on |λ|(k)
my putStrLn(k & " -> " & keyValue(rec, k))
end |λ|
end script
-- follow each argument name and value with line feed
map(showKVpair, allKeys(rec)) as string
end namedArgs
-- TEST
on run
intercalate(linefeed, ¬
{positionalArgs(["alpha", "beta", "gamma", "delta"]), ¬
namedArgs({epsilon:27, zeta:48, eta:81, theta:8, iota:1})})
--> "alpha
-- beta
-- gamma
-- delta
--
-- epsilon -> 27
-- eta -> 81
-- iota -> 1
-- zeta -> 48
-- theta -> 8
-- "
end run
-- GENERIC FUNCTIONS
-- putStrLn :: a -> String
on putStrLn(a)
(a as string) & linefeed
end putStrLn
-- map :: (a -> b) -> [a] -> [b]
on map(f, xs)
tell mReturn(f)
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to |λ|(item i of xs, i, xs)
end repeat
return lst
end tell
end map
-- intercalate :: Text -> [Text] -> Text
on intercalate(strText, lstText)
set {dlm, my text item delimiters} to {my text item delimiters, strText}
set strJoined to lstText as text
set my text item delimiters to dlm
return strJoined
end intercalate
-- allKeys :: Record -> [String]
on allKeys(rec)
(current application's NSDictionary's dictionaryWithDictionary:rec)'s allKeys() as list
end allKeys
-- keyValue :: Record -> String -> Maybe String
on keyValue(rec, strKey)
set ca to current application
set v to (ca's NSDictionary's dictionaryWithDictionary:rec)'s objectForKey:strKey
if v is not missing value then
item 1 of ((ca's NSArray's arrayWithObject:v) as list)
else
missing value
end if
end keyValue
-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: Handler -> Script
on mReturn(f)
if class of f is script then
f
else
script
property |λ| : f
end script
end if
end mReturn</syntaxhighlight>
{{Out}}
<pre>"alpha
beta
gamma
delta
epsilon -> 27
eta -> 81
iota -> 1
zeta -> 48
theta -> 8
"</pre>
=={{header|Applesoft BASIC}}==
An array of parameters with a count as parameter zero can be used in a subroutine to simulate a variadic function. The values in the array should probably be cleared when the subroutine returns because the array is a global variable.
<syntaxhighlight lang="applesoftbasic">10 P$(0) = STR$(5)
20 P$(1) = "MARY"
30 P$(2) = "HAD"
40 P$(3) = "A"
50 P$(4) = "LITTLE"
60 P$(5) = "LAMB"
70 GOSUB 90"VARIADIC FUNCTION
80 END
90 FOR I = 1 TO VAL(P$(0)) : ? P$(I) : P$(I) = "" : NEXT I : P$(0) = "" : RETURN</syntaxhighlight>
=={{header|Arturo}}==
<syntaxhighlight lang="rebol">;-------------------------------------------
; a quasi-variadic function
;-------------------------------------------
variadic: function [args][
loop args 'arg [
print arg
]
]
; calling function with one block param
; and the arguments inside
variadic ["one" 2 "three"]
;-------------------------------------------
; a function with optional attributes
;-------------------------------------------
variable: function [args][
print ["args:" args]
if? attr? "with" [
print ["with:" attr "with"]
]
else [
print "without attributes"
]
]
variable "yes"
variable.with:"something" "yes!"</syntaxhighlight>
{{out}}
<pre>one
2
three
args: yes
without attributes
args: yes!
with: something</pre>
=={{header|AutoHotkey}}==
{{works with|AutoHotkey_L}}
Writing an asterisk after the final parameter marks the function as variadic, allowing it to receive a variable number of parameters:
<syntaxhighlight lang="autohotkey">printAll(args*) {
for k,v in args
t .= v "`n"
MsgBox, %t%
}</syntaxhighlight>
This function can be called with any number of arguments:<syntaxhighlight lang="autohotkey">printAll(4, 3, 5, 6, 4, 3)
printAll(4, 3, 5)
printAll("Rosetta", "Code", "Is", "Awesome!")</syntaxhighlight>
An array of parameters can be passed to any function by applying the same syntax to a function-call:<syntaxhighlight lang="autohotkey">args := ["Rosetta", "Code", "Is", "Awesome!"]
printAll(args*)</syntaxhighlight>
'''AutoHotkey Basic (deprecated):'''
Function arguments can be given default values. Comparison with "" can indicate that an argument was present (and not of value ""). As of version 1.0.48, you can pass more parameters than defined by a function, in which case the parameters are evaluated but discarded. Versions earlier than that produce warnings.
<syntaxhighlight lang="autohotkey">string = Mary had a little lamb
StringSplit, arg, string, %A_Space%
Line 52 ⟶ 352:
Function(arg1="",arg2="",arg3="",arg4="",arg5="") {
If arg%A_Index% !=
out .= arg%A_Index% "`n"
}</
=={{header|AWK}}==
AWK allows
This f() can accept 0 to 3 arguments.
<syntaxhighlight lang="awk">function f(a, b, c){
if (a != "") print a
if (b != "") print b
if (c != "") print c
}
BEGIN {
print "[1 arg]"; f(1)
print "[2 args]"; f(1, 2)
print "[3 args]"; f(1, 2, 3)
}</syntaxhighlight>
<pre>[1 arg]
1
[2 args]
1
2
[3 args]
1
2
3</
This f() can also accept array elements. This works because any missing array elements default to "", so f() ignores them.
<syntaxhighlight lang="awk">function f(a, b, c) {
if (a != "") print a
if (b != "") print b
if (c != "") print c
}
BEGIN {
# Set ary[1] and ary[2] at runtime.
split("Line 1:Line 2", ary, ":")
# Pass to f().
f(ary[1], ary[2], ary[3])
}</syntaxhighlight>
<pre>Line 1
Line 2</pre>
Functions like f() can take only a few arguments. To accept more arguments, or to accept "" as an argument, the function must take an array, and the caller must bundle its arguments into an array. This g() accepts 0 or more arguments in an array.
<syntaxhighlight lang="awk">function g(len, ary, i) {
for (i = 1; i <= len; i++) print ary[i];
}
BEGIN {
c = split("Line 1:Line 2:Next line is empty::Last line", a, ":")
g(c, a) # Pass a[1] = "Line 1", a[4] = "", ...
}</syntaxhighlight>
<pre>Line 1
Line 2
Next line is empty
Last line</pre>
=={{header|BaCon}}==
Variable argument lists are defined with the keyword '''VAR''', and are passed as an indexed array of strings. The number of elements is specified by a SIZE parameter. ''Arguments to functions could also simply be indexed or associative arrays or multiple element delimited strings.''
<syntaxhighlight lang="freebasic">' Variadic functions
OPTION BASE 1
SUB demo (VAR arg$ SIZE argc)
LOCAL x
PRINT "Amount of incoming arguments: ", argc
FOR x = 1 TO argc
PRINT arg$[x]
NEXT
END SUB
' No argument
demo(0)
' One argument
demo("abc")
' Three arguments
demo("123", "456", "789")</syntaxhighlight>
{{out}}
<pre>prompt$ bacon variadic.bac
Converting 'variadic.bac'... done, 16 lines were processed in 0.003 seconds.
Compiling 'variadic.bac'... cc -c variadic.bac.c
cc -o variadic variadic.bac.o -lbacon -lm
Done, program 'variadic' ready.
prompt$ ./variadic
Amount of incoming arguments: 0
Amount of incoming arguments: 1
abc
Amount of incoming arguments: 3
123
456
789</pre>
=={{header|BASIC}}==
Line 78 ⟶ 466:
The parameter list does not pass information about parameter type. If necessary, the type information has to be passed for example in the first parameter.
C calling convention has to be used (with keyword cdecl).
<
DIM arg AS Any Ptr
DIM i AS Integer
Line 89 ⟶ 477:
END SUB
printAll 3, 3.1415, 1.4142, 2.71828</
For some reason, I was not able to get a Strings version of the above to work.
==={{header|FreeBASIC}}===
String version
<syntaxhighlight lang="freebasic">' version 15-09-2015
' compile with: fbc -s console
Sub printAll_string Cdecl (count As Integer, ... )
Dim arg As Any Ptr
Dim i As Integer
arg = va_first()
For i = 1 To count
Print *Va_Arg(arg, ZString Ptr)
arg = va_next(arg, ZString Ptr)
Next i
End Sub
' ------=< MAIN >=------
' direct
printAll_string (5, "Foxtrot", "Romeo", "Echo", "Echo", "BASIC")
' strings
Print : Print
Dim As String a = "one", b = "two", c = "three"
printAll_string (3, a, b, c)
' count is smaller then the number of arguments, no problem
Print : Print
printAll_string (1, a, b, c)
' count is greater then the number of arguments
' after the last valid argument garbage is displayed
' should be avoided, could lead to disaster
Print : Print
printAll_string (4, a, b, c)
Print
' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End</syntaxhighlight>
{{out}}
<pre>only the last example shown
one
two
three
…À�”ÀƒÄ��¶À÷ØÃ���¡<"A</pre>
{{works with|Beta BASIC|3.0}}
{{works with|SAM BASIC}}
Line 98 ⟶ 532:
The parameters are read with READ command just like when reading conventional DATA statements.
The existence of more parameters as well as the type of each parameter can be checked with function ITEM().
<syntaxhighlight lang="zxbasic">100 DEF PROC printAll DATA
110 DO UNTIL ITEM()=0
120 IF ITEM()=1 THEN
Line 111 ⟶ 545:
200 printAll 3.1415, 1.4142, 2.71828
210 printAll "Mary", "had", "a", "little", "lamb",</syntaxhighlight>
The code above is for Beta BASIC. There is a small difference between Beta BASIC and SAM BASIC.
On Beta BASIC, the function ITEM has empty parenthesis, on SAM BASIC the parenthesis are not used.
See also: [[Varargs#RapidQ|RapidQ]]
=={{header|Batch File}}==
<syntaxhighlight lang="dos">
@echo off
:_main
call:_variadicfunc arg1 "arg 2" arg-3
pause>nul
:_variadicfunc
setlocal
for %%i in (%*) do echo %%~i
exit /b
:: Note: if _variadicfunc was called from cmd.exe with arguments parsed to it, it would only need to contain:
:: @for %%i in (%*) do echo %%i
</syntaxhighlight>
{{out}}
<pre>
arg1
arg 2
arg-3
</pre>
=={{header|bc}}==
To simulate a variadic function one would define a function which takes an array as parameter and
:a) a second parameter for the actual number of arguments,
:b) uses a special value which marks the end or
:c) the first element in the array specifies the number of arguments.
<syntaxhighlight lang="bc">/* Version a */
define f(a[], l) {
auto i
for (i = 0; i < l; i++) a[i]
}
/* Version b */
define g(a[]) {
auto i
for (i = 0; a[i] != -1; i++) a[i]
}
/* Version c */
define h(a[]) {
auto i
for (i = 1; i <= a[0]; i++) a[i]
}</syntaxhighlight>
=={{header|BCPL}}==
BCPL does not have true variadic functions, however, it is explicitly legal
to pass a function the "wrong" amount of arguments. If fewer arguments are passed
than declared, the rest will remain uninitialized, if too many are passed,
the excess arguments are ignored. Additionally, it is guaranteed that the arguments will be located sequentially
in memory, starting from the first, making it possible to treat the address of the
first argument as if it is in fact an array of arguments.
These two facts together make it easy to declare a "variadic" function by
simply specifying a whole bunch of dummy arguments in the declaration, and then calling
the function later on with however many you happen to need. At least as many arguments as
you declare are guaranteed to make it through, though any more will not necessarily.
This technique is used in the standard library (this is how <code>writef</code>, the
equivalent to C's <code>printf</code>, is defined), and the book <cite>BCPL: The Language
and its Compiler</cite> by BCPL designer Martin Richards (which is as official as it gets)
explicitly introduces this technique.
<syntaxhighlight lang="bcpl">get "libhdr"
// A, B, C, etc are dummy arguments. If more are needed, more can be added.
// Eventually you will run into the compiler limit.
let foo(num, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O) be
// The arguments can be indexed starting from the first one.
for i=1 to num do writef("%S*N", (@num)!i)
// You can pass as many arguments as you want. The declaration above guarantees
// that at least the first 16 arguments (including the number) will be available,
// but you certainly needn't use them all.
let start() be
foo(5, "Mary", "had", "a", "little", "lamb")</syntaxhighlight>
{{out}}
<pre>Mary
had
a
little
lamb</pre>
=={{header|BQN}}==
All BQN functions can be variadic since they allow taking lists of arbitrary length as arguments. A function can reject variadicity by defining a header to restrict the arguments to a specific length.
<syntaxhighlight lang="bqn">Fun1 ← •Show¨
Fun2 ← {•Show¨𝕩}
Fun3 ← { 1=≠𝕩 ? •Show 𝕩; "too many arguments " ! 𝕩}</syntaxhighlight>
Both <tt>Fun1</tt> and <tt>Fun2</tt> display all the values (arguments) of the lists given to them.
<tt>Fun3</tt> throws an error if the given argument is not a list of length 1 or not a list at all. Otherwise it displays its argument.
=={{header|C}}==
The ANSI C standard header <tt>stdarg.h</tt> defines macros for low-level access to the parameter stack. It does not know the number or types of these parameters; this is specified by the required initial parameter(s). For example, it could be a simple count, a terminating <tt>NULL</tt>, or a more complicated parameter specification like a printf() format string.
<
#include <stdarg.h>
Line 132 ⟶ 665:
}
varstrings(5, "Mary", "had", "a", "little", "lamb");</
In C, there is no way to call a variadic function on a list of arguments constructed at runtime.
Line 141 ⟶ 674:
The actual implementation of <tt>va_list</tt> is implementation-dependent. If you are developing on a specific platform, you may use platform-specific knowledge to create a <tt>va_list</tt> by hand in a non-portable way. For example, on many platforms, a <tt>va_list</tt> is simply a pointer to a buffer where the arguments are arranged contiguously in memory.
=={{header|C sharp|C#}}==
<syntaxhighlight lang="csharp">using System;
class Program {
static void Main(string[] args) {
PrintAll("test", "rosetta code", 123, 5.6);
}
static void PrintAll(params object[] varargs) {
foreach (var i in varargs) {
Console.WriteLine(i);
}
}
}</syntaxhighlight>
Output:
<pre>test
rosetta code
123
5.6</pre>
=={{header|C++}}==
Line 147 ⟶ 703:
* An important difference is that enums are distinct types with possibly different representation than int in C++, but enumeration values are still converted to <code>int</code> when passed to varargs. Therefore they have to be accessed as <code>int</code> in <code>va_arg</code>.
{{works with|g++|4.3.0}} using option -std=c++0x
<
template<typename T>
Line 171 ⟶ 727:
std::string s = "Hello world";
print("i = ", i, " and s = \"", s, "\"\n");
}</
As the example shows, variadic templates allow any type to be passed.
=={{header|Clojure}}==
<
(doseq [a args]
(println a)))
(foo :bar :baz :quux)
(apply foo [:bar :baz :quux])</
=={{header|COBOL}}==
{{works with|Micro Focus COBOL V3.2}}
<syntaxhighlight lang="text">
program-id. dsp-str is external.
data division.
linkage section.
1 cnt comp-5 pic 9(4).
1 str pic x.
procedure division using by value cnt
by reference str delimited repeated 1 to 5.
end program dsp-str.
program-id. variadic.
procedure division.
call "dsp-str" using 4 "The" "quick" "brown" "fox"
stop run
.
end program variadic.
program-id. dsp-str.
data division.
working-storage section.
1 i comp-5 pic 9(4).
1 len comp-5 pic 9(4).
1 wk-string pic x(20).
linkage section.
1 cnt comp-5 pic 9(4).
1 str1 pic x(20).
1 str2 pic x(20).
1 str3 pic x(20).
1 str4 pic x(20).
1 str5 pic x(20).
procedure division using cnt str1 str2 str3 str4 str5.
if cnt < 1 or > 5
display "Invalid number of parameters"
stop run
end-if
perform varying i from 1 by 1
until i > cnt
evaluate i
when 1
unstring str1 delimited low-value
into wk-string count in len
when 2
unstring str2 delimited low-value
into wk-string count in len
when 3
unstring str3 delimited low-value
into wk-string count in len
when 4
unstring str4 delimited low-value
into wk-string count in len
when 5
unstring str5 delimited low-value
into wk-string count in len
end-evaluate
display wk-string (1:len)
end-perform
exit program
.
end program dsp-str.
</syntaxhighlight>
{{out}}
<pre>
The
quick
brown
fox
</pre>
=={{header|Common Lisp}}==
Line 210 ⟶ 814:
The [http://www.lispworks.com/documentation/HyperSpec/Body/03_dac.htm <tt>&rest</tt>] [http://www.lispworks.com/documentation/HyperSpec/Body/03_da.htm lambda list keyword] causes all remaining arguments to be bound to the following variable.
<
(dolist (arg args)
(print arg)))
Line 217 ⟶ 821:
(let ((args '("Mary" "had" "a" "little" "lamb")))
(apply #'example args))</
=={{header|Coq}}==
To define a variadic function, we build a variadic type:
<syntaxhighlight lang="coq">
Fixpoint Arity (A B: Set) (n: nat): Set := match n with
|O => B
|S n' => A -> (Arity A B n')
end.
</syntaxhighlight>
This function can be used as a type, Arity A B n means <math>\underbrace{A \rightarrow \cdots \rightarrow A}_{\text{n times}} \rightarrow B</math> .
Hence each functions that takes an arbitrary number n of parameter of type A and returns B will have the type Arity A B n (Note that we can parameter n to be a specific value) <br \>
Those functions will be called with their first parameters yielding the number of arguments and the rest being the arguments themselves.
Since Arity is a type, we can compound it with itself as the destination to mean, for instance, "n naturals and 2 * n booleans" like so:
<syntaxhighlight lang="coq">
Definition nat_twobools (n: nat) := Arity nat (Arity bool nat (2*n)) n.
</syntaxhighlight>
There is no equivalent to printf in Coq, because this function has border effects. We will then instead of printing each arguments build a list from it. <br \>
Our function has type Arity A (list A) n and we obviously want to use induction on n.
To build the heritance, we will have the hypothesis of Arity A (list A) n and will have to build a term of Arity A (list A) (S n).
Forall A and B, Arity A B (S n) is but <math>A \rightarrow \text{Arity A B n}</math>, aka a function that takes A and returns an Arity A B n <br \>
Hence to introduce a new value, we simply create a function that takes one parameter and uses it. <br \>
Finally, for the function to work, we need an accumulator of some sort
<syntaxhighlight lang="coq">
Require Import List.
Fixpoint build_list_aux {A: Set} (acc: list A) (n : nat): Arity A (list A) n := match n with
|O => acc
|S n' => fun (val: A) => build_list_aux (acc ++ (val :: nil)) n'
end.
</syntaxhighlight>
Our function is then just an application of this one:
<syntaxhighlight lang="coq">
Definition build_list {A: Set} := build_list_aux (@nil A).
</syntaxhighlight>
To call it we give it the number of argument and then the parameters we want in the list
<syntaxhighlight lang="coq">
Check build_list 5 1 2 5 90 42.
</syntaxhighlight>
Which gives the result [1; 2; 5; 90; 42]
If instead of a list we wanted a vector (a list which size is now in its own type), then it gets trickier. <br \>
One of the problem is that we will have to prove equality of types such as one of the types t A n and t A (n + 0).
We '''should not''' use lemmas or automatic tactics in this case.
The reason for that is that the proof will be then a part of the type and computation of our function, so when we will try to compute it, Coq will be unable to unfold the opaque proof. Instead we should define our own lemmas and set their opacity to be transparent. Here are the two lemmas we will need:
<syntaxhighlight lang="coq">
Lemma transparent_plus_zero: forall n, n + O = n.
intros n; induction n.
- reflexivity.
- simpl; rewrite IHn; trivial.
Defined.
Lemma transparent_plus_S: forall n m, n + S m = S n + m .
intros n; induction n; intros m.
- reflexivity.
- simpl; f_equal; rewrite IHn; reflexivity.
Defined.
</syntaxhighlight>
Now on to the function. <br \>
Here the accumulator has to be of a fixed size, so we give this size a value, and for each step, we decrement the number of argument and increment this size.
The size of the result is the sum of the size of the accumulator and of the current number of argument. This sum is constant.
Instead of defining a function directly, we will construct it as a proof that will be easier for us to write:
<syntaxhighlight lang="coq">
Require Import Vector.
Definition build_vector_aux {A: Set} (n: nat): forall (size_acc : nat) (acc: t A size_acc), Arity A (t A (size_acc + n)) n.
induction n; intros size_acc acc.
- rewrite transparent_plus_zero; apply acc. (*Just one argument, return the accumulator*)
- intros val. rewrite transparent_plus_S. apply IHn. (*Here we use the induction hypothesis. We just have to build the new accumulator*)
apply shiftin; [apply val | apply acc]. (*Shiftin adds a term at the end of a vector*)
</syntaxhighlight>
As before, we can now build the full function with a null accumulator:
<syntaxhighlight lang="coq">
Definition build_vector {A: Set} (n: nat) := build_vector_aux n O (@nil A).
</syntaxhighlight>
When we call it:
<syntaxhighlight lang="coq">
Require Import String.
Eval compute in build_vector 4 "Hello" "how" "are" "you".
</syntaxhighlight>
Which gives the vector of members "Hello", "how", "are" and "you" of size 4
=={{header|D}}==
<
void printAll(TyArgs...)(TyArgs args) {
foreach (el; args)
}
// Typesafe variadic function for dynamic array
void showSum1(int[] items...) {
items.sum.writeln;
}
// Typesafe variadic function for fixed size array
void showSum2(int[4] items...) {
items[].sum.writeln;
}
void main() {
printAll(4, 5.6, "Rosetta", "Code", "
writeln;
showSum1(1, 3, 50);
showSum2(1, 3, 50, 10);
}</syntaxhighlight>
{{out}}
<pre>4
5.6
Rosetta
Code
is
awesome
54
64</pre>
Being a system language, in D there are also:
* C-style variadic functions
* D-style variadic functions with type info
* Typesafe variadic function for class objects
See for more info: http://dlang.org/function.html
=={{header|Delphi}}==
''See [[#Free Pascal|Free Pascal]].''
=={{header|Dyalect}}==
<syntaxhighlight lang="dyalect">func printAll(args...) {
for i in args {
print(i)
}
}
printAll("test", "rosetta code", 123, 5.6)</syntaxhighlight>
{{out}}
<pre>test
rosetta code
123
5.6</pre>
=={{header|Déjà Vu}}==
Variadic functions in the Déjà Vu standard library generally end with <code>(</code>, <code>[</code> or <code>{</code>. For this purpose, <code>)</code>, <code>]</code> and <code>}</code> are autonyms (that is, they have a global bindings to themselves, so that <code>)</code> is the same as <code>:)</code>).
<syntaxhighlight lang="dejavu">show-all(:
while /= ) dup:
!.
drop
show-all( :foo "Hello" 42 [ true ] )</syntaxhighlight>
{{out}}
<pre>:foo
"Hello"
42
[ true ]</pre>
=={{header|E}}==
Line 244 ⟶ 998:
However, accepting any number of arguments can easily be done, as it is just a particular case of the basic mechanism for dynamic message handling:
<
match [`run`, args] {
for x in args {
Line 254 ⟶ 1,008:
example("Mary", "had", "a", "little", "lamb")
E.call(example, "run", ["Mary", "had", "a", "little", "lamb"])</
For comparison, a plain method doing the same thing for exactly two arguments would be like this:
<
to run(x, y) {
println(x)
println(y)
}
}</
or, written using the function syntax,
<
println(x)
println(y)
}</
=={{header|Ecstasy}}==
Ecstasy does not support a true variadic function (<i>a la</i> C with "<tt>...</tt>") or a syntactic sugar for the same (<i>a la</i> Java with "<tt>...</tt>" and the underlying <tt>Object[]</tt>). Instead, when a variadic call is needed, the method or function is declared with the desired array type, and the caller simply passes an array value of any length using the literal array syntax:
<syntaxhighlight lang="java">
module VariadicFunction {
void show(String[] strings) {
@Inject Console console;
strings.forEach(s -> console.print(s));
}
void run() {
show(["hello", "world"]);
String s1 = "not";
String s2 = "a";
String s3 = "constant";
String s4 = "literal";
show([s1, s2, s3, s4]);
}
}
</syntaxhighlight>
{{out}}
<pre>
hello
world
not
a
constant
literal
</pre>
=={{header|Egel}}==
Egel performs almost all of its work with pattern-matching anonymous functions which may match against any number of arguments. The following combinator discriminates between 2, 1, or 0 arguments; more elaborate examples are straightforward.
<syntaxhighlight lang="egel">
[ X Y -> "two" | X -> "one" | -> "zero" ]
</syntaxhighlight>
=={{header|Elena}}==
ELENA 6.x :
<syntaxhighlight lang="elena">import system'routines;
import extensions;
extension variadicOp
{
printAll(params object[] list)
{
for(int i := 0; i < list.Length; i++)
{
self.printLine(list[i])
}
}
}
public program()
{
console.printAll("test", "rosetta code", 123, 5.6r)
}</syntaxhighlight>
{{out}}
<pre>
test
rosetta code
123
5.6
</pre>
=={{header|Elixir}}==
Elixir doesn't have the feature of the variable number of arguments.
However, it is possible to process as the list if putting in an argument in [].
<syntaxhighlight lang="elixir">defmodule RC do
def print_each( arguments ) do
Enum.each(arguments, fn x -> IO.inspect x end)
end
end
RC.print_each([1,2,3])
RC.print_each(["Mary", "had", "a", "little", "lamb"])</syntaxhighlight>
{{out}}
<pre>
1
2
3
"Mary"
"had"
"a"
"little"
"lamb"
</pre>
=={{header|Emacs Lisp}}==
An <code>&rest</code> in the formal parameters gives all further arguments in a list, which the code can then act on in usual list ways. Fixed arguments can precede the <code>&rest</code> if desired.
<syntaxhighlight lang="lisp">(defun my-print-args (&rest arg-list)
(message "there are %d argument(s)" (length arg-list))
(dolist (arg arg-list)
(message "arg is %S" arg)))
(my-print-args 1 2 3)</syntaxhighlight>
A function can be called with a list of arguments (and optionally fixed arguments too) with <code>apply</code>, similar to most Lisp variants.
<syntaxhighlight lang="lisp">(let ((arg-list '("some thing %d %d %d" 1 2 3)))
(apply 'message arg-list))</syntaxhighlight>
=={{header|EMal}}==
<syntaxhighlight lang="emal">
^|EMal supports variadic functions in more than one way|^
fun print = void by text mode, List args do
writeLine("== " + mode + " ==")
for each var arg in args do writeLine(arg) end
end
fun printArgumentsList = void by List args
print("accepting a list", args)
end
fun printArgumentsUnchecked = void by some var args
print("unchecked variadic", args)
end
fun printArgumentsChecked = void by text subject, logic isTrue, int howMany, some text values
print("checked variadic", var[subject, isTrue, howMany, +values]) # unary plus on lists does list expansion
end
printArgumentsList(var["These are the ", true, 7, "seas", "of", "Rhye"])
printArgumentsUnchecked("These are the ", true, 7, "seas", "of", "Rhye")
printArgumentsChecked("These are the ", true, 7, "seas", "of", "Rhye")
</syntaxhighlight>
{{out}}
<pre>
== accepting a list ==
These are the
⊤
7
seas
of
Rhye
== unchecked variadic ==
These are the
⊤
7
seas
of
Rhye
== checked variadic ==
These are the
⊤
7
seas
of
Rhye
</pre>
=={{header|Erlang}}==
Variable amount of anything (like arguments): use a list.
<syntaxhighlight lang="erlang">
print_each( Arguments ) -> [io:fwrite( "~p~n", [X]) || X <- Arguments].
</syntaxhighlight>
=={{header|Euler Math Toolbox}}==
<syntaxhighlight lang="euler math toolbox">
>function allargs () ...
$ loop 1 to argn();
$ args(#),
$ end
$endfunction
>allargs(1,3,"Test",1:2)
1
3
Test
[ 1 2 ]
>function args test (x) := {x,x^2,x^3}
>allargs(test(4))
4
16
64
</syntaxhighlight>
=={{header|Euphoria}}==
<syntaxhighlight lang="euphoria">procedure print_args(sequence args)
for i = 1 to length(args) do
puts(1,args[i])
puts(1,' ')
end for
end procedure
print_args({"Mary", "had", "a", "little", "lamb"})</syntaxhighlight>
=={{header|F Sharp|F#}}==
<syntaxhighlight lang="fsharp">
// Variadic function. Nigel Galloway: March 6th., 2024
open System
type X()=static member F([<ParamArray>] args: Object[]) = args|>Array.iter(printfn "%A")
X.F(23, 3.142, "Nigel", 1u, true)
</syntaxhighlight>
{{output}}
<pre>
23
3.142
Nigel
1
true
</pre>
=={{header|Factor}}==
Variadic functions can be created by making a word which accepts a number specifying how many data stack items to operate on.
<syntaxhighlight lang="factor">MACRO: variadic-print ( n -- quot ) [ print ] n*quot ;</syntaxhighlight>
An interactive demonstration in the listener:
<syntaxhighlight lang="factor">IN: scratchpad "apple" "banana" "cucumber"
--- Data stack:
"apple"
"banana"
"cucumber"
IN: scratchpad 2 variadic-print
cucumber
banana
--- Data stack:
"apple"</syntaxhighlight>
=={{header|Forth}}==
Words taking variable numbers of arguments may be written by specifying the number of parameters to operate upon as the top parameter. There are two standard words which operate this way: PICK and ROLL.
<
4 3 2 1 4 sum . \ 10</
Alternatively, you can operate upon the entire parameter stack for debugging by using the word DEPTH, which returns the number of items currently on the stack.
<
=={{header|Fortran}}==
Line 289 ⟶ 1,265:
The following code shows how an optional vector argument can be used to pass a variable number of argument to a subroutine.
<
integer, dimension(:), allocatable :: va
Line 321 ⟶ 1,297:
end subroutine v_func
end program varargs</
=={{header|Free Pascal}}==
Note, strictly speaking the routine <tt>writeLines</tt> has exactly ''one'' parameter.
<syntaxhighlight lang="pascal">program variadicRoutinesDemo(input, output, stdErr);
{$mode objFPC}
// array of const is only supported in $mode objFPC or $mode Delphi
procedure writeLines(const arguments: array of const);
var
argument: TVarRec;
begin
// inside the body `array of const` is equivalent to `array of TVarRec`
for argument in arguments do
begin
with argument do
begin
case vType of
vtInteger:
begin
writeLn(vInteger);
end;
vtBoolean:
begin
writeLn(vBoolean);
end;
vtChar:
begin
writeLn(vChar);
end;
vtAnsiString:
begin
writeLn(ansiString(vAnsiString));
end;
// and so on
end;
end;
end;
end;
begin
writeLines([42, 'is', true, #33]);
end.</syntaxhighlight>
{{out}}
<syntaxhighlight lang="text">42
is
TRUE
!</syntaxhighlight>
=={{header|Fōrmulæ}}==
{{FormulaeEntry|page=https://formulae.org/?script=examples/Variadic_function}}
'''Solution'''
Fōrmulæ does not have variadic functions. However an array can be provided as argument:
'''Examples'''
Tee following function accepts a list as its unique parameter. It retrieves the list in vertical form (as a matrix of 1 column):
[[File:Fōrmulæ - Variadic function 01.png]]
[[File:Fōrmulæ - Variadic function 02.png]]
[[File:Fōrmulæ - Variadic function 03.png]]
[[File:Fōrmulæ - Variadic function 04.png]]
[[File:Fōrmulæ - Variadic function 05.png]]
With this approach we can use several parameters being lists with variable number of elements each, for example:
[[File:Fōrmulæ - Variadic function 06.png]]
[[File:Fōrmulæ - Variadic function 07.png]]
[[File:Fōrmulæ - Variadic function 08.png]]
=={{header|FutureBasic}}==
<syntaxhighlight lang="futurebasic">void local fn Function1( count as long, ... )
va_list ap
long value
va_start( ap, count )
while ( count )
value = fn va_argLong( ap )
printf @"%ld",value
count--
wend
va_end( ap )
end fn
void local fn Function2( obj as CFTypeRef, ... )
va_list ap
va_start( ap, obj )
while ( obj )
printf @"%@",obj
obj = fn va_argObj(ap)
wend
va_end( ap )
end fn
window 1
// params: num of args, 1st arg, 2nd arg, etc.
fn Function1( 3, 987, 654, 321 )
print
// params: 1st arg, 2nd arg, ..., NULL
fn Function2( @"One", @"Two", @"Three", @"O'Leary", NULL )
HandleEvents</syntaxhighlight>
{{Out}}
<pre>987
654
321
One
Two
Three
O'Leary</pre>
=={{header|Go}}==
<syntaxhighlight lang="go">func printAll(things ... string) {
// it's as if you declared "things" as a []string, containing all the arguments
for _, x := range things {
fmt.Println(x)
}
}</
If you wish to supply an argument list to a variadic function at runtime, you can do this by adding a <code>...</code> ''after'' a slice argument:
<syntaxhighlight lang="go">args := []string{"foo", "bar"}
printAll(args...)</syntaxhighlight>
=={{header|Golo}}==
<syntaxhighlight lang="golo">#!/usr/bin/env golosh
----
This module demonstrates variadic functions.
----
module Variadic
import gololang.Functions
----
Varargs have the three dots after them just like Java.
----
function varargsFunc = |args...| {
foreach arg in args {
println(arg)
}
}
function main = |args| {
varargsFunc(1, 2, 3, 4, 5, "against", "one")
# to call a variadic function with an array we use the unary function
unary(^varargsFunc)(args)
}</syntaxhighlight>
=={{header|Groovy}}==
<
printAll(1, 2, "three", ["3", "4"])</
Sample output:
Line 351 ⟶ 1,477:
=={{header|Haskell}}==
You can use some fancy recursive type-class instancing to make a function that takes an unlimited number of arguments. This is how, for example, printf works in Haskell.
<
process :: [String] -> t
Line 367 ⟶ 1,493:
main = do printAll 5 "Mary" "had" "a" "little" "lamb"
printAll 4 3 5
printAll "Rosetta" "Code" "Is" "
So here we created a type class specially for the use of this variable-argument function. The type class specifies a function, which takes as an argument some kind of accumulated state of the arguments so far, and returns the type of the type class. Here I chose to accumulate a list of the string representations of each of the arguments; this is not the only way to do it; for example, you could choose to print them directly and just accumulate the IO monad.
We need two kinds of instances of this type class. There is the "base case" instance, which has the type that can be thought of as the "return type" of the vararg function. It describes what to do when we are "done" with our arguments. Here we just take the accumulated list of strings and print them, one per line
We actually wanted to use "IO ()" instead of "IO a"; but since you can't instance just a specialization like "IO ()", we used "IO a" but return "undefined" to make sure nobody uses it. Or we can use GADTs pragma and constraint in instance like this :
<syntaxhighlight lang="haskell">{-# LANGUAGE GADTs #-}
...
instance a ~ () => PrintAllType (IO a) where
process args = do mapM_ putStrLn args
...</syntaxhighlight>
You can have multiple base case instances; for example, you might want an instances that returns the result as a string instead of printing it. This is how "printf" in Haskell can either print to stdout or print to string (like sprintf in other languages), depending on the type of its context.
The other kind of instance is the "recursive case". It describes what happens when you come across an argument. Here we simply append its string representation to the end of our previous "accumulated state", and then pass that state onto the next iteration. Make sure to specify the requirements of the types of the arguments; here I just required that each argument be an instance of Show (so you can use "show" to get the string representation), but it might be different for you.
==
varargs.icn
<
varargs("some", "extra", "args")
write()
Line 386 ⟶ 1,521:
procedure varargs(args[])
every write(!args)
end</
Using it
Line 398 ⟶ 1,533:
c
d</pre>
=={{header|Insitux}}==
<syntaxhighlight lang="insitux">(function f
(print (join "\n" args)))
(f 1 2 3 4)</syntaxhighlight>
=={{header|Io}}==
<
=={{header|J}}==
Line 410 ⟶ 1,549:
For example:
<
B=:3
C=:5
sum=:+/
sum 1,A,B,4,C
15</
That said, J expects that members of lists all use the same kind of machine representation. If you want both character literals and numbers for arguments, or if you want arrays with different dimensions, each argument must be put into a box, and the function is responsible for dealing with the packing material.
<
commaAnd 'dog';A;B;'cat';C
dog, 2, 3, cat and 5</
To print each argument on its own line, we would typically map <code>echo</code> over the arguments (in this example, the contents of each box):
<syntaxhighlight lang="j"> echo&>'dog';A;B;'cat';C
dog
2
3
cat
5</syntaxhighlight>
=={{header|Java}}==
{{works with|Java|1.5+}}
Using <tt>...</tt> after the type of argument will take in any number of arguments and put them all in one array of the given type with the given name.
<
// "things" is an Object[]
for(Object i:things){
System.out.println(i);
}
}</
This function can be called with any number of arguments:
<
printAll(4, 3, 5);
printAll("Rosetta", "Code", "Is", "
Or with an array directly (the array must have the appropriate array type; i.e. if it is <tt>String...</tt>, then you need to pass a <tt>String[]</tt>):
<
printAll(args);</
But not with both (in this case the array is considered as just one of two arguments, and not expanded):
<
printAll(args, "Dude!");//does not print "Rosetta Code Is Awesome, Dude!"
//instead prints the type and hashcode for args followed by "Dude!"</
In some rare cases, you may want to pass an array as just a single argument, but doing it directly would expand it to be the entire argument. In this case, you need to cast the array to <tt>Object</tt> (all arrays are objects) so the compiler doesn't know it's an array anymore.
<syntaxhighlight lang="java5">printAll((Object)args);</syntaxhighlight>
=={{header|JavaScript}}==
===ES5===
The [https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Functions/arguments <code>arguments</code>] special variable, when used inside a function, contains an array of all the arguments passed to that function.
<
for (var i=0; i<arguments.length; i++)
print(arguments[i])
Line 453 ⟶ 1,606:
printAll(4, 3, 5, 6, 4, 3);
printAll(4, 3, 5);
printAll("Rosetta", "Code", "Is", "
The <code><var>function</var>.arguments</code> property is equivalent to the <code>arguments</code> variable above, but is deprecated.
You can use the <tt>apply</tt> method of a function to apply it to a list of arguments:
<
printAll.apply(null, args)</
===ECMAScript 2015 (ES6) variants===
The newest version of ECMAScript added fat arrow function expression syntax, rest arguments and the spread operator. These make writing something like this easy. Of course, a better version might use Array.prototype.map, but here we have a variant that works on variadic arguments:
<syntaxhighlight lang="javascript">let
fix = // Variant of the applicative order Y combinator
f => (f => f(f))(g => f((...a) => g(g)(...a))),
forAll =
f =>
fix(
z => (a,...b) => (
(a === void 0)
||(f(a), z(...b)))),
printAll = forAll(print);
printAll(0,1,2,3,4,5);
printAll(6,7,8);
(f => a => f(...a))(printAll)([9,10,11,12,13,14]);
// 0
// 1
// 2
// 3
// 4
// 5
// 6
// 7
// 8
// 9
// 10
// 11
// 12
// 13
// 14
</syntaxhighlight>
Or, less ambitiously:
<syntaxhighlight lang="javascript">(() => {
'use strict';
// show :: a -> String
const show = x => JSON.stringify(x, null, 2);
// printAll [any] -> String
const printAll = (...a) => a.map(show)
.join('\n');
return printAll(1, 2, 3, 2 + 2, "five", 6);
})();</syntaxhighlight>
{{Out}}
<pre>1
2
3
4
"five"
6</pre>
=={{header|jq}}==
jq does not support variadic functions, but all versions of jq allow JSON arrays and objects to be used as arguments and as
inputs of functions, and thus variadic functions can easily be simulated. In addition, as described in the next subsection, recent releases of jq support variadic function names.
The first task requirement can in effect be accomplished using a 0-arity function defined as follows:
<syntaxhighlight lang="jq">def demo: .[];</syntaxhighlight>
The parameters would be presented to <code>demo</code> in the form of an array. For example, given an array, args, constructed at runtime, the second task requirement can be accomplished by calling:
<syntaxhighlight lang="jq">args | demo</syntaxhighlight>
For example:
<syntaxhighlight lang="jq">["cheese"] + [3.14] + [[range(0;3)]] | demo</syntaxhighlight>
produces:
<syntaxhighlight lang="sh">"cheese"
3.14
[0,1,2]</syntaxhighlight>
'''Variadic Function Names''':
In this subsection, the notation f/n will be used to refer to a function named f with arity n. For example, recurse/1 is a builtin function that requires one argument.
In recent releases of jq (after version 1.4), function names are variadic in the sense that, if f is a function name, then f/n can be defined for multiple values of n. However, jq does not support the programmatic construction of function calls, and if a function is called with an undefined name/arity combination, then an error will be raised.
<syntaxhighlight lang="jq">
# arity-0:
def f: "I have no arguments";
# arity-1:
def f(a1): a1;
# arity-1:
def f(a1;a2): a1,a2;
def f(a1;a2;a3): a1,a2,a3;
# Example:
f, f(1), f(2;3), f(4;5;6)</syntaxhighlight>
produces:
<syntaxhighlight lang="sh">1
2
3
4
5
6</syntaxhighlight>
=={{header|Julia}}==
Putting <code>...</code> after the last argument in a function definition makes it variadic (any number of arguments are passed as a tuple):
<syntaxhighlight lang="julia">
julia> print_each(X...) = for x in X; println(x); end
julia> print_each(1, "hello", 23.4)
1
hello
23.4
</syntaxhighlight>
Conversely, when <code>...</code> is appended to an array (or other iterable object) passed to the function, the array is converted to a sequence of arguments:
<syntaxhighlight lang="julia">
julia> args = [ "first", (1,2,17), "last" ]
3-element Array{Any,1}:
"first"
(1,2,17)
"last
julia> print_each(args...)
first
(1,2,17)
last
</syntaxhighlight>
=={{header|Klingphix}}==
<syntaxhighlight lang="klingphix">:varfunc
1 tolist flatten
len [
get print nl
] for
drop
;
"Enter any number of words separated by space: " input nl
stklen [split varfunc nl] if
nl "End " input</syntaxhighlight>
=={{header|Kotlin}}==
<syntaxhighlight lang="scala">// version 1.1
fun variadic(vararg va: String) {
for (v in va) println(v)
}
fun main(args: Array<String>) {
variadic("First", "Second", "Third")
println("\nEnter four strings for the function to print:")
val va = Array(4) { "" }
for (i in 1..4) {
print("String $i = ")
va[i - 1] = readLine()!!
}
println()
variadic(*va)
}</syntaxhighlight>
Sample input/output:
{{out}}
<pre>
First
Second
Third
Enter four strings for the function to print:
String 1 = Animal
String 2 = Vegetable
String 3 = Mineral
String 4 = Whatever
Animal
Vegetable
Mineral
Whatever
</pre>
=={{header|Ksh}}==
<syntaxhighlight lang="ksh">
#!/bin/ksh
# Variadic function
# # Variables:
#
typeset -a arr=( 0 2 4 6 8 )
# # Functions:
#
function _variadic {
while [[ -n $1 ]]; do
print $1
shift
done
}
######
# main #
######
_variadic Mary had a little lamb
echo
_variadic ${arr[@]}</syntaxhighlight>
{{out}}<pre>
Mary
had
a
little
lamb
0
2
4
6
8</pre>
=={{header|Lambdatalk}}==
Lambdas are de facto variadic in lambdatalk
<syntaxhighlight lang="scheme">
{def foo
{lambda {:s} // :s will get any sequence of words
{S.first :s}
{if {S.empty? {S.rest :s}} then else {foo {S.rest :s}}}}}
-> foo
{foo hello brave new world}
-> hello brave new world
{foo {S.serie 1 10}}
-> 1 2 3 4 5 6 7 8 9 10
</syntaxhighlight>
=={{header|Lang}}==
<syntaxhighlight lang="lang">
fp.printAll = (&values...) -> {
fn.arrayForEach(&values, fn.println)
}
fp.printAll(1, 2, 3)
# 1
# 2
# 3
fp.printAll() # No output
fp.printAll(abc, def, xyz)
# abc
# def
# xyz
# Array un-packing
&arr $= [1, abc, xyz, 42.42f]
fp.printAll(&arr...)
# 1
# abc
# xyz
# 42.42
fp.printAll(&arr..., last)
# 1
# abc
# xyz
# 42.42
# last
fp.printAll(first, &arr...)
# first
# 1
# abc
# xyz
# 42.42
</syntaxhighlight>
Solution with the use of arguments auto-pack operator and combinator function:
<syntaxhighlight lang="lang">
fp.printAllComb $= -|fn.combC(fn.arrayForEach, fn.println)
fp.printAllComb(42, 2, abc)
# 42
# 2
# abc
fp.printAllComb() # No output
&arr $= [1, abc, xyz, 42.42f]
fp.printAllComb(&arr...)
# 1
# abc
# xyz
# 42.42
</syntaxhighlight>
=={{header|Lasso}}==
A Lasso method parameter name can prefixed by "..." to specify a variable number of parameters, which are made available as a staticarray. If no name is specified, the staticarray will be named "rest".
<syntaxhighlight lang="lasso">define printArgs(...items) => stdoutnl(#items)
define printEachArg(...) => with i in #rest do stdoutnl(#i)
printArgs('a', 2, (:3))
printEachArg('a', 2, (:3))</syntaxhighlight>
To expand an existing list, pass it to the method using invocation syntax.
<syntaxhighlight lang="lasso">local(args = (:"Rosetta", "Code", "Is", "Awesome!"))
printEachArg(:#args)</syntaxhighlight>
Output:
<syntaxhighlight lang="lasso">staticarray(a, 2, staticarray(3))
a
2
staticarray(3)
Rosetta
Code
Is
Awesome!</syntaxhighlight>
=={{header|Logo}}==
Line 467 ⟶ 1,932:
# an optional "rest" input (a list containing a colon prefixed word, set to the list of remaining arguments)
# ...with an optional default arity (a number)
<
foreach :args [print ?]
end
(varargs "Mary "had "a "little "lamb)
apply "varargs [Mary had a little lamb]</
=={{header|Lua}}==
The generic syntax for defining a variadic function is appending an ellipsis to the list of arguments:
<syntaxhighlight lang="lua">function varar(...)
for i, v in ipairs{...} do print(v) end
end</
It is then used like so:
<syntaxhighlight lang="lua">varar(1, "bla", 5, "end");</syntaxhighlight>
{{out}}
<pre>1
bla
5
end</pre>
When used with runtime arrays, the unpack function must be called on the array, otherwise the array itself will be used as the only argument:
<syntaxhighlight lang="lua">local runtime_array = {1, "bla", 5, "end"};
varar(unpack(runtime_array));</syntaxhighlight>
=={{header|M2000 Interpreter}}==
Each function has own stack of values. We can Read arguments from there, using a Read statement or we can check stack or do anything to it. This stack erased when function exit.
We can use parenthesis in the name or not. When we use parentesis we can put some arguments, but interpreter make a Read statement with these arguments.
Function Variadic() {...} is the same as Function Variadic {...} and Function Variadic () {...}.
Function Abc(x, y) {...} is the same as Function Abc {Read x, y : ... }
We can use Read at some point after some statement executed in Abc function. We can check the stack before the Read to find the type of values in function's stack. This stack isn't the return or process stack.
Module's have stack too, but calling a module from module pass the same stack. This hold if we call function using Call statement.
<syntaxhighlight lang="m2000 interpreter">
Module CheckIt {
\\ Works for numbers and strings (letters in M2000)
Function Variadic {
\\ print a letter for each type in function stack
Print Envelope$()
\\Check types using Match
Print Match("NNSNNS")
=stack.size
While not Empty {
if islet then {print letter$} else print number
}
}
M=Variadic(1,2,"Hello",3,4,"Bye")
Print M
\\ K is a poiner to Array
K=(1,2,"Hello 2",3,4,"Bye 2")
\\ !K pass all items to function's stack
M=Variadic(!K)
}
Checkit
Module CheckIt2 {
Function Variadic {
\\ [] return a pointer to stack, and leave a new stack as function's stack
a=[]
\\ a is a pointer to stack
\\ objects just leave a space, and cursor move to next column (spread on lines)
Print a
}
M=Variadic(1,2,"Hello",3,4,"Bye")
Print M
\\ K is a poiner to Array
K=(1,2,"Hello 2",3,4,"Bye 2")
\\ !K pass all items to function stack
M=Variadic(!K)
}
Checkit2
</syntaxhighlight>
=={{header|M4}}==
<
`ifelse($1,0,`',`$2
$0(decr($1),shift(shift($@)))')')dnl
Line 489 ⟶ 2,025:
define(`x',`1,2')
define(`y',`,3,4,5')
showargs(x`'y)</
Output (with tracing):
Line 508 ⟶ 2,044:
</pre>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
Function that takes 0 to infinite arguments and prints the arguments:
<
Example:
<
ShowMultiArg[a, b, c]
ShowMultiArg[5, 3, 1]</
gives back:
<
a
Line 524 ⟶ 2,060:
5
3
1</
In general Mathematica supports patterns in functions, mostly represented by the blanks and sequences: _, __ and ___ . With those you can create functions with variable type and number of arguments.
=={{header|MATLAB}}==
In MATLAB, the keyword "varargin" in the argument list of a function denotes that function as a variadic function. This keyword must come last in the list of arguments. "varargin" is actually a cell-array that assigns a comma separated list of input arguments as elements in the list. You can access each of these elements like you would any normal cell array.
<syntaxhighlight lang="matlab">function variadicFunction(varargin)
for i = (1:numel(varargin))
disp(varargin{i});
end
end</syntaxhighlight>
Sample Usage:
<syntaxhighlight lang="matlab">>> variadicFunction(1,2,3,4,'cat')
1
2
3
4
cat</syntaxhighlight>
=={{header|Maxima}}==
<syntaxhighlight lang="maxima">show([L]) := block([n], n: length(L), for i from 1 thru n do disp(L[i]))$
show(1, 2, 3, 4);
apply(show, [1, 2, 3, 4]);
/* Actually, the built-in function "disp" is already what we want */
disp(1, 2, 3, 4);
apply(disp, [1, 2, 3, 4]);</syntaxhighlight>
=={{header|Metafont}}==
Line 531 ⟶ 2,102:
Variable number of arguments to a macro can be done using the <tt>text</tt> keyword identifying the kind of argument to the macro. In this way, each argument can be of any kind (here, as example, I show all the primitive types that Metafont knows)
<
for x = t:
if unknown x: message "unknown value"
Line 544 ⟶ 2,115:
print_arg("hello", x, 12, fullcircle, currentpicture, down, identity, false, pencircle);
end</
=={{header|Modula-3}}==
Modula-3 provides the built ins <tt>FIRST</tt> and <tt>LAST</tt>, which can be used with <tt>FOR</tt> loops to cycle over all elements of an array. This, combined with open arrays allows Modula-3 to simulate variadic functions.
<
IMPORT IO;
Line 563 ⟶ 2,134:
BEGIN
Variable(strings);
END Varargs.</
Output:
<pre>
Line 573 ⟶ 2,144:
</pre>
Things get more complicated if you want to mix types:
<
IMPORT IO, Fmt;
Line 598 ⟶ 2,169:
strings^ := "Rosetta"; ints^ := 1; reals^ := 3.1415;
Variable(refarr);
END Varargs.</
Output:
<pre>
Line 605 ⟶ 2,176:
3.1415
</pre>
=={{header|Nemerle}}==
{{trans|C#}}
Like C#, Nemerle uses the <tt>params</tt> keyword to specify that arguments are collected into an array.
<syntaxhighlight lang="nemerle">using System;
using System.Console;
module Variadic
{
PrintAll (params args : array[object]) : void
{
foreach (arg in args) WriteLine(arg);
}
Main() : void
{
PrintAll("test", "rosetta code", 123, 5.6, DateTime.Now);
}
}</syntaxhighlight>
=={{header|Nim}}==
<syntaxhighlight lang="nim">proc print(xs: varargs[string, `$`]) =
for x in xs:
echo x</syntaxhighlight>
The function can be called with any number of arguments and the argument list can be constructed at runtime:
<syntaxhighlight lang="nim">print(12, "Rosetta", "Code", 15.54321)
print 12, "Rosetta", "Code", 15.54321, "is", "awesome!"
let args = @["12", "Rosetta", "Code", "15.54321"]
print(args)</syntaxhighlight>
=={{header|Objective-C}}==
Objective-C uses the same varargs functionality as C. Like C, it has no way of knowing the number or types of the arguments. When the arguments are all objects, the convention is that, if the number of arguments is undetermined, then the list must be "terminated" with <code>nil</code>. Functions that follow this convention include the constructors of data structures that take an undetermined number of elements, like <code>[NSArray arrayWithObjects:...]</code>.
<
void logObjects(id firstObject, ...) // <-- there is always at least one arg, "nil", so this is valid, even for "empty" list
Line 622 ⟶ 2,224:
// This function can be called with any number or type of objects, as long as you terminate it with "nil":
logObjects(@"Rosetta", @"Code", @"Is", @"
logObjects(@4, @3, @"foo", nil);</syntaxhighlight>
=={{header|OCaml}}==
OCaml's strong type system makes writing variadic functions complex, as there is no <code>'a... -> 'b</code> type.
In general, writing a function that takes a list as argument is the best practice :
<syntaxhighlight lang="ocaml">let rec print = function
| [] -> ()
| x :: xs -> print_endline x; print xs
(* Or better yet *)
let print = List.iter print_endline
let () =
print [];
print ["hello"; "world!"]</syntaxhighlight>
If you really need a true variadic function, there are a few ways to make it work.
The first is to specify the function's type with its first argument using a generalized algebraic data type (GADT) :
<syntaxhighlight lang="ocaml">type 'a variadic =
| Z : unit variadic
| S : 'a variadic -> (string -> 'a) variadic
let rec print : type a. a variadic -> a = function
| Z -> ()
| S v -> fun x -> Format.printf "%s\n" x; print v
let () =
print Z; (* no arguments *)
print (S Z) "hello"; (* one argument *)
print (S (S (S Z))) "how" "are" "you" (* three arguments *)</syntaxhighlight>
You can even specify different types with more GADT constructors:
<syntaxhighlight lang="ocaml">type 'a variadic =
| Z : unit variadic
| U : 'a variadic -> (unit -> 'a) variadic
| S : 'a variadic -> (string -> 'a) variadic
| I : 'a variadic -> (int -> 'a) variadic
| F : 'a variadic -> (float -> 'a) variadic
(* Printing of a general type, takes pretty printer as argument *)
| G : 'a variadic -> (('t -> unit) -> 't -> 'a) variadic
| L : 'a variadic -> (('t -> unit) -> 't list -> 'a) variadic
let rec print : type a. a variadic -> a = function
| Z -> ()
| U v -> fun () -> Format.printf "()\n"; print v
| S v -> fun x -> Format.printf "%s\n" x; print v
| I v -> fun x -> Format.printf "%d\n" x; print v
| F v -> fun x -> Format.printf "%f\n" x; print v
| G v -> fun pp x -> pp x; print v
| L v -> fun pp x -> List.iter pp x; print v
let () =
print (S (I (S Z))) "I am " 5 "Years old";
print (S (I (S (L (S Z))))) "I have " 3 " siblings aged " (print (I Z)) [1;3;7]</syntaxhighlight>
This is what the <code>Format.printf</code> functions do. The only difference is that the compiler constructs the GADT term from the given format string. This is why you can only call them with an explicit string argument, and not a variable of type string.
Another method uses continuation passing style (CPS) :
<syntaxhighlight lang="ocaml">let print f = f ()
let arg value () cont = cont (Format.printf "%s\n" value)
let stop a = a
let () =
print stop;
print (arg "hello") (arg "there") stop;
(* use a prefix operator for arg *)
let (!) = arg
let () =
print !"hello" !"hi" !"its" !"me" stop</syntaxhighlight>
This isn't really a variadic function though, it's a hack that looks like one. The work is being done in the <code>arg</code> function, not <code>print</code>.
Other example (sequential composition or Lisp-like <code>apply</code>).
<syntaxhighlight lang="ocaml">type ('f,'g) t =
| Z : ('f,'f) t
| S : 'a -> (('a -> 'f), ('f,'g) t -> 'g) t
let rec apply: type f g. f -> (f,g) t -> g =
fun k t -> match t with
| Z -> k (* type g = f *)
| S x -> apply (k x) (* type g = (f,g) t -> g *)
let (!) x = S x (* prefix *)
(* top level *)
# apply List.map !(fun x -> x+1) ![1;2;3] Z</syntaxhighlight>
=={{header|Oforth}}==
As Oforth uses a data stack, the only way to have a function using a variable number of parameters is to define one of its parameters as the number of parameters to use on the stack.
For instance :
<syntaxhighlight lang="oforth">: sumNum(n) | i | 0 n loop: i [ + ] ;</syntaxhighlight>
{{out}}
<pre>
sumNum(3, 1, 2, 3) println
6
sumNum(2, 1, 4) println
5
sumNum(5, 3, 4, 5, 6, 7) println
25
</pre>
=={{header|Oz}}==
This is only possible for methods, not for functions/procedures.
<
class Demo from BaseObject
meth test(...)=Msg
Line 643 ⟶ 2,345:
in
{D test(1 2 3 4)}
{D Constructed}</
=={{header|PARI/GP}}==
A variadic function can be coded directly in PARI using the parser code <code>s*</code>.
{{Works with|PARI/GP|2.8+}}
<syntaxhighlight lang="parigp">f(a[..])=for(i=1,#a,print(a[i]))</syntaxhighlight>
{{Works with|PARI/GP|2.8.1+}}
<syntaxhighlight lang="parigp">call(f, v)</syntaxhighlight>
=={{header|Pascal}}==
Standard Pascal does not allow variadic functions.
''See [[#Free Pascal|Free Pascal]] instead.''
=={{header|Perl}}==
Functions in Perl 5 don't have argument lists. All arguments are stored in the array <tt>@_</tt> anyway, so there is variable arguments by default.
<
foreach (@_) {
print "$_\n";
}
}</
This function can be called with any number of arguments:
<
print_all(4, 3, 5);
print_all("Rosetta", "Code", "Is", "
Since lists are flattened when placed in a list context, you can just pass an array in as an argument and all its elements will become separate arguments:
<
print_all(@args);</
Introduced '''experimentally''' in 5.20.0, subroutines can have signatures when the feature is turned on:
<syntaxhighlight lang="perl">use 5.020;
use experimental 'signatures';</syntaxhighlight>
Perl policy states that all bets are off with experimental features—their behavior is subject to change at any time, and they may even be removed completely (''this feature will most likely stay in, but expect changes in the future that will break any scripts written using it as it stands in 5.20.1'').
Functions can be declared with fixed arity:
<syntaxhighlight lang="perl">sub print ($x, $y) {
say $x, "\n", $y;
}</syntaxhighlight>
But this can easily be converted to a variadic function with a slurpy parameter:
<syntaxhighlight lang="perl">sub print_many ($first, $second, @rest) {
say
."Second: $second\n"
."And the rest: "
. join("\n", @rest);
}</syntaxhighlight>
It is valid for the @rest array to be empty, so this is also an optional parameter (see [[Optional parameters]]).
=={{header|Phix}}==
{{libheader|Phix/basics}}
Copy of [[Variadic_function#Euphoria|Euphoria]]. The argument to print_args could be anything constructed at runtime. You can also specify optional parameters, simply by specifying a default value. Any non-optional arguments must be grouped together at the start.
<!--<syntaxhighlight lang="phix">-->
<span style="color: #008080;">procedure</span> <span style="color: #000000;">print_args</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">args</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">args</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">args</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #000000;">print_args</span><span style="color: #0000FF;">({</span><span style="color: #008000;">"Mary"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"had"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"a"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"little"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"lamb"</span><span style="color: #0000FF;">})</span>
<!--</syntaxhighlight>-->
=={{header|Phixmonti}}==
<syntaxhighlight lang="phixmonti">def varfunc
1 tolist flatten
len for
get print nl
endfor
enddef
"Mary" "had" "a" "little" "lamb" 5 tolist varfunc</syntaxhighlight>
=={{header|PHP}}==
PHP 4 and above supports varargs. You can deal with the argument list using the <tt>func_num_args()</tt>, <tt>func_get_arg()</tt>, and <tt>func_get_args()</tt> functions.
<syntaxhighlight lang="php"><?php
function printAll() {
foreach (func_get_args() as $x) // first way
echo "$x\n";
Line 708 ⟶ 2,434:
printAll(4, 3, 5, 6, 4, 3);
printAll(4, 3, 5);
printAll("Rosetta", "Code", "Is", "
?></syntaxhighlight>
You can use the <tt>call_user_func_array</tt> function to apply it to a list of arguments:
<syntaxhighlight lang="php"><?php
$args = array("Rosetta", "Code", "Is", "Awesome!");
call_user_func_array('printAll', $args);
?></syntaxhighlight>
{{works with|PHP|5.6+}}
You can receive variable arguments in a list by having a parameter preceded by <tt>...</tt>:
<syntaxhighlight lang="php"><?php
function printAll(...$things) {
foreach ($things as $x)
echo "$x\n";
}
printAll(4, 3, 5, 6, 4, 3);
printAll(4, 3, 5);
printAll("Rosetta", "Code", "Is", "Awesome!");
?></syntaxhighlight>
You can use the same <tt>...</tt> syntax to supply a list of arguments to a function:
<syntaxhighlight lang="php"><?php
$args = ["Rosetta", "Code", "Is", "Awesome!"];
printAll(...$args);
?></syntaxhighlight>
=={{header|PicoLisp}}==
The '@' operator causes a function to accept a variable number of arguments.
These can be accesed with the
'[http://software-lab.de/doc/refA.html#args args]',
'[http://software-lab.de/doc/refN.html#next next]',
'[http://software-lab.de/doc/refA.html#arg arg]' and
'[http://software-lab.de/doc/refR.html#rest rest]' functions.
<syntaxhighlight lang="picolisp">(de varargs @
(while (args)
(println (next)) ) )</syntaxhighlight>
The '@' operator may be used in combination with normal parameters:
<syntaxhighlight lang="picolisp">(de varargs (Arg1 Arg2 . @)
(println Arg1)
(println Arg2)
(while (args)
(println (next)) ) )</syntaxhighlight>
It is called like any other function
<syntaxhighlight lang="picolisp">(varargs 'a 123 '(d e f) "hello")</syntaxhighlight>
also by possibly applying it to a ready-made list
<syntaxhighlight lang="picolisp">(apply varargs '(a 123 (d e f) "hello"))</syntaxhighlight>
Output in all cases:
<pre>a
123
(d e f)
"hello"</pre>
=={{header|PL/I}}==
<syntaxhighlight lang="pli">/* PL/I permits optional arguments, but not an infinitely varying */
/* argument list: */
s: procedure (a, b, c, d);
declare (a, b, c, d
if ^omitted(a) then put skip list (a);
if ^omitted(b) then put skip list (b);
if ^omitted(c) then put skip list (c);
if ^omitted(d) then put skip list (d);
end s;</syntaxhighlight>
=={{header|Plain English}}==
The only built-in imperative in Plain English that has variadic arguments is the 'call' imperative:
<syntaxhighlight lang="text">Call [dll name] [dll function] with [a value] and [another value].</syntaxhighlight>
The number of arguments used in the statement varies on the number of arguments needed by the DLL function. Variadic functions cannot be user-defined.
=={{header|PowerShell}}==
<
foreach ($x in $args) {
Write-Host $x
}
}</
Normal usage of the function just uses all arguments one after another:
<syntaxhighlight lang
In PowerShell v1 there was no elegant way of using an array of objects as arguments to a function which leads to the following idiom:
<
Invoke-Expression "& print_all $array"</
PowerShell v2 introduced the splat operator which makes this easier:
{{works with|PowerShell|2}}
<syntaxhighlight lang
=={{header|Prolog}}==
The Prolog standard does not require support for variadic functions,
but there is no need for them in Prolog, because Prolog has first-class support for terms, including lists and terms such as (1,2,3), which are also
known as comma-lists.
For example, the standard predicate ''write/1'' has just one formal
argument, but it will accept any term. Thus, except for the
additional parentheses, ''write/1'' is like a variadic function that
requires at least one argument:
<pre>
?- write( (1) ), nl.
1
?- write( (1,2,3) ), nl.
1,2,3
</pre>
In practice, since the minimum length of a comma-list is 2, Prolog
lists are often used instead of comma-lists to handle situations where
vararg-behavior is wanted. For example:
<syntaxhighlight lang="prolog">printAll( List ) :- forall( member(X,List), (write(X), nl)).
</syntaxhighlight>
To handle more esoteric situations, we could define a higher-order predicate to handle terms of arbitrary arity, e.g.
<syntaxhighlight lang="prolog">
execute( Term ) :-
Term =.. [F | Args],
forall( member(X,Args), (G =.. [F,X], G, nl) ).
</syntaxhighlight>
<pre>
?- execute( write(1,2,3) ).
1
2
3
</pre>
=={{header|Python}}==
Putting <tt>*</tt> before an argument will take in any number of arguments and put them all in a tuple with the given name.
<
for x in things:
print x</
This function can be called with any number of arguments:
<
print_all(4, 3, 5)
print_all("Rosetta", "Code", "Is", "
You can use the same "*" syntax to apply the function to an existing list of arguments:
<
print_all(*args)</
===Keyword arguments ===
Python also has keyword arguments were you can add arbitrary ''func('''''keyword1=value1, keyword2=value2 ...''''')'' keyword-value pairs when calling a function.
This example shows both keyword arguments and positional arguments. The two calls to the function are equivalent. '''*alist''' spreads the members of the list to create positional arguments, and '''**adict''' does similar for the keyword/value pairs from the dictionary.
<
print "POSITIONAL ARGS:\n " + "\n ".join(repr(x) for x in positionalargs)
print "KEYWORD ARGS:\n " + '\n '.join(
Line 786 ⟶ 2,598:
'fee' = 'fi'
'fo' = 'fum'
>>></
See the Python entry in [[Named_Arguments#Python|Named Arguments]] for a more comprehensive description of Python function parameters and call arguments.
=={{header|Qi}}==
Qi doesn't have support for variable argument functions, but we can fake it by using a macro that
puts all arguments into a list.
<syntaxhighlight lang="qi">
(define varargs-func
A -> (print A))
(define varargs
[varargs | Args] -> [varargs-func [list | Args]]
A -> A)
(sugar in varargs 1)
</syntaxhighlight>
=={{header|Quackery}}==
A Quackery word can take a variable number of items from the stack, either by specifying the number of items on the top of stack, or by placing a marker on the stack underneath a number of items.
(<code>oats</code>: "'''o'''ne '''a'''nd '''t'''he '''s'''ame" compares the ''identity'' of two items, ensuring that <code>marker</code> is uniquely identified.)
<syntaxhighlight lang="quackery">[ pack witheach
[ echo$ cr ] ] is counted-echo$ ( $ ... n --> )
[ this ] is marker ( --> m )
[ []
[ swap dup marker oats
iff drop done
nested swap join
again ] ] is gather ( m x ... --> [ )
[ gather witheach
[ echo$ cr ] ] is markered-echo$ ( m $ ... --> )
$ "this" $ "is" $ "a" $ "formica" $ "table" 5 counted-echo$
cr
marker $ "green" $ "is" $ "its" $ "colour" markered-echo$</syntaxhighlight>
{{out}}
<pre>this
is
a
formica
table
green
is
its
colour
</pre>
=={{header|R}}==
This first function, almost completes the task, but the formatting isn't quite as specified.
<
printallargs1(1:5, "abc", TRUE)
# [[1]]
Line 801 ⟶ 2,668:
#
# [[3]]
# [1] TRUE</
This function is corrrect, though a little longer.
<
{
args <- list(...)
Line 812 ⟶ 2,679:
# [1] 1 2 3 4 5
# [1] "abc"
# [1] TRUE</
Use do.call to call a function with a list of arguments.
<
do.call(mean, arglist)</
=={{header|
The following defines and uses an any-number-of-arguments variadic
function called "vfun".
<syntaxhighlight lang="racket">
-> (define (vfun . xs) (for-each displayln xs))
-> (vfun)
-> (vfun 1)
1
-> (vfun 1 2 3 4)
1
2
3
4
-> (apply vfun (range 10 15))
10
11
12
13
14
</syntaxhighlight>
=={{header|Raku}}==
(formerly Perl 6)
{{works with|Rakudo|#25 "Minneapolis"}}
If a subroutine has no formal parameters but mentions the variables <code>@_</code> or <code>%_</code> in its body, it will accept arbitrary positional or keyword arguments, respectively. You can even use both in the same function.
<syntaxhighlight lang="raku" line>sub foo {
.say for @_;
say .key, ': ', .value for %_;
}
foo 1, 2, command => 'buckle my shoe',
3, 4, order => 'knock at the door';</syntaxhighlight>
This prints:
<pre>1
2
3
4
command: buckle my shoe
order: knock at the door</pre>
Raku also supports slurpy arrays and hashes, which are formal parameters that consume extra positional and keyword arguments like <code>@_</code> and <code>%_</code>. You can make a parameter slurpy with the <code>*</code> twigil. This implementation of <code>&foo</code> works just like the last:
<syntaxhighlight lang="raku" line>sub foo (*@positional, *%named) {
.say for @positional;
say .key, ': ', .value for %named;
}</syntaxhighlight>
Unlike in Perl 5, arrays and hashes aren't flattened automatically. Use the <code>|</code> operator to flatten:
<syntaxhighlight lang="raku" line>foo |@ary, |%hsh;</syntaxhighlight>
=={{header|RapidQ}}==
RapidQ uses special keywords SUBI and FUNCTIONI for procedures and functions with variable number of parameters.
Numeric parameters are accessed from array ParamVal and string parameters from array ParamStr$.
<
FOR i = 1 TO ParamValCount
PRINT ParamVal(i)
Line 917 ⟶ 2,755:
printAll 4, 3, 5, 6, 4, 3
printAll 4, 3, 5
printAll "Rosetta", "Code", "Is", "
=={{header|REALbasic}}==
This subroutine prints it arguments. ParamArrays must be the last argument but may be preceded by any number of normal arguments.
<syntaxhighlight lang="vb">
Sub PrintArgs(ParamArray Args() As String)
For i As Integer = 0 To Ubound(Args)
Print(Args(i))
Next
End Sub
</syntaxhighlight>
Calling the subroutine.
<syntaxhighlight lang="vb">
PrintArgs("Hello", "World!", "Googbye", "World!")
</syntaxhighlight>
=={{header|REBOL}}==
REBOL does not have variadic functions, nevertheless, it is easy to define a function taking just one argument, an ARGS block. The ARGS block contents can then be processed one by one:
<syntaxhighlight lang="rebol">REBOL [
Title: "Variadic Arguments"
]
print-all: func [
args [block!] {the arguments to print}
] [
foreach arg args [print arg]
]
print-all [rebol works this way]</syntaxhighlight>
=={{header|REXX}}==
===simplistic===
<syntaxhighlight lang="rexx">print_all: procedure /* [↓] is the # of args passed.*/
do j=1 for arg()
say arg(j)
end /*j*/
return</syntaxhighlight>
===annotated===
<syntaxhighlight lang="rexx">print_all: procedure /* [↓] is the # of args passed.*/
do j=1 for arg()
say '[argument' j"]: " arg(j)
end /*j*/
return</syntaxhighlight>
===invocations===
The function can be called with any number of arguments (including no arguments and/or omitted arguments),
<br>although some REXX implementations impose a limit and the number of arguments.
<syntaxhighlight lang="rexx">call print_all .1,5,2,4,-3, 4.7e1, 013.000 ,, 8**2 -3, sign(-66), abs(-71.00), 8 || 9, 'seven numbers are prime, 8th is null'
call print_all "One ringy-dingy,",
"two ringy-dingy,",
"three ringy-dingy...",
"Hello? This is Ma Bell.",
"Have you been misusing your instrument?",
"(Lily Tomlin routine)"
/* [↑] example showing multi-line arguments.*/</syntaxhighlight>
===dynamically built argument list===
<syntaxhighlight lang="rexx">/* REXX */
list=''
Do i=1 To 6
list=list||'"arg"'i','
End
list=list||'"end"'
Interpret 'call show' list
Exit
show: procedure
do j=1 for arg()
say arg(j)
end /*j*/
return</syntaxhighlight>
Output:
<pre>arg1
arg2
arg3
arg4
arg5
arg6
end</pre>
=={{header|Ring}}==
<syntaxhighlight lang="ring">
# Project : Variadic function
sum([1,2])
sum([1,2,3])
nums = [1,2,3,4]
sum(nums)
func sum(nums)
total = 0
for num = 1 to len(nums)
total = total + num
next
showarray(nums)
see " " + total + nl
func showarray(vect)
see "["
svect = ""
for n = 1 to len(vect)
svect = svect + vect[n] + " "
next
svect = left(svect, len(svect) - 1)
see "" + svect + "]"
</syntaxhighlight>
Output:
<pre>
[1 2] 3
[1 2 3] 6
[1 2 3 4] 10
</pre>
=={{header|RPL}}==
Variable number of arguments are idiomatically passed through the stack, with the last argument specifying how many items shall be taken into account.
{{works with|HP|48G}}
≪ ""
1 ROT '''START'''
" " ROT + SWAP +
'''END''' TAIL
≫ '<span style="color:blue">MKLINE</span>' STO
"Mary" "has" "a" "little" "lamb" 5 <span style="color:blue">MKLINE</span>
{{out}}
<pre>
1: "Mary has a little lamb"
</pre>
=={{header|Ruby}}==
The * is sometimes referred to as the "splat" in Ruby.
<
end</
This function can be called with any number of arguments:
<
print_all(4, 3, 5)
print_all("Rosetta", "Code", "Is", "
You can use the same "*" syntax to apply the function to an existing list of arguments:
<
print_all(*args)</
=={{header|Rust}}==
<syntaxhighlight lang="rust">// 20220106 Rust programming solution
macro_rules! print_all {
($($args:expr),*) => { $( println!("{}", $args); )* }
}
fn main() {
print_all!("Rosetta", "Code", "Is", "Awesome!");
}</syntaxhighlight>
Output: [https://tio.run/##PYy9CoMwAIT3PMUpDokIWocOlRZKp66@gIQ2lUB@JIm0IHn2VCt0uYPj@87NPqRU12ibtm0OzRH9umBydnRca2lGeKvmIK0hRPOHs4OblfDZikgTBq4UFgKAFrTgbvQn8Zkcq0qG8wULCrqDymQ0X2Je4UexDqxEBImEvAw0l4ay/ej/uwq99SIEvlr5zT7F1ne/5fUtvNUiy1lHYkpf Try it online!]
=={{header|Scala}}==
<
Example:
Line 972 ⟶ 2,942:
Putting a dot before the last argument will take in any number of arguments and put them all in a list with the given name.
<
(for-each
(lambda (x) (display x) (newline))
things))</
Note that if you define the function anonymously using <tt>lambda</tt>, and you want all the args to be collected in one list (i.e. you have no parameters before the parameter that collects everything), then you can just replace the parentheses altogether with that parameter, as if to say, let this be the argument list:
<
(lambda things
(for-each
(lambda (x) (display x) (newline))
things)))</
This function can be called with any number of arguments:
<
(print-all 4 3 5)
(print-all "Rosetta" "Code" "Is" "
The <tt>apply</tt> function will apply the function to a list of arguments:
<
(apply print-all args)</
=={{header|Sidef}}==
A parameter declared with "*", can take any number of arguments of any type.
<syntaxhighlight lang="ruby">func print_all(*things) {
things.each { |x| say x };
}</syntaxhighlight>
This function can be called with any number of arguments:
<syntaxhighlight lang="ruby">print_all(4, 3, 5, 6, 4, 3);
print_all(4, 3, 5);
print_all("Rosetta", "Code", "Is", "Awesome!");</syntaxhighlight>
Also, there is "..." which transforms an array into a list of arguments.
<syntaxhighlight lang="ruby">var args = ["Rosetta", "Code", "Is", "Awesome!"];
print_all(args...);</syntaxhighlight>
=={{header|Slate}}==
Line 998 ⟶ 2,981:
Putting an asterisk before a method's input variable header name means it will contain all non-core input variables (those are prefixed with a colon) in an Array.
<
printAll applyTo: #(4 3 5 6 4 3).
printAll applyTo: #('Rosetta' 'Code' 'Is' 'Awesome!').</
For method definitions and message sends, the same mechanism is employed, but the syntax for passing arguments after the message phrase is special (using commas to append arguments which fill <tt>*rest</tt>):
<
lobby printAll, 4, 3, 5, 6, 4, 3.
lobby printAll, 'Rosetta', 'Code', 'Is', 'Awesome!'.
</syntaxhighlight>
=={{header|Swift}}==
Using <tt>...</tt> after the type of argument will take in any number of arguments and put them all in one array of the given type with the given name.
<syntaxhighlight lang="swift">func printAll<T>(things: T...) {
// "things" is a [T]
for i in things {
print(i)
}
}</syntaxhighlight>
This function can be called with any number of arguments:
<syntaxhighlight lang="swift">printAll(4, 3, 5, 6, 4, 3)
printAll(4, 3, 5)
printAll("Rosetta", "Code", "Is", "Awesome!")</syntaxhighlight>
=={{header|Tcl}}==
{{works with|Tcl|8.5}}
If the last argument is named "args", it collects all the remaining arguments
<
print_all 4 3 5 6 4 3
Line 1,021 ⟶ 3,017:
print_all $things ;# ==> incorrect: passes a single argument (a list) to print_all
print_all {*}$things ;# ==> correct: passes each element of the list to the procedure</
The above code will work in all versions of Tcl except for the last line. A version-independent transcription of that (one of many possible) would be:
<
=={{header|TIScript}}==
In TIScript last parameter of function may have '..' added to its name. On call that parameter will contain an array of rest of arguments passed to that function.
<syntaxhighlight lang="javascript">
function printAll(separator,argv..) {
if(argv.length)
stdout.print(argv[0]);
for (var i=1; i < argv.length; i++)
stdout.print(separator, argv[i]);
}
printAll(" ", 4, 3, 5, 6, 4, 3);
printAll(",", 4, 3, 5);
printAll("! ","Rosetta", "Code", "Is", "Awesome");</syntaxhighlight>
=={{header|uBasic/4tH}}==
It's not easy to make a variadic function or procedure in uBasic/4tH, but it is possible with a little effort, provided the stack is used. However, sometimes it is required to reverse the order of the values by loading them into the array, from high memory to low memory. Strings may require even more effort, but the built-in hashing helps.
<syntaxhighlight lang="text">Push _Mary, _had, _a, _little, _lamb ' Push the hashes
Proc _PrintStrings (5) ' Print the string
Push 1, 4, 5, 19, 12, 3 ' Push the numbers
Print "Maximum is: ";FUNC(_Max(6)) ' Call the function
End
_PrintStrings Param(1) ' Print a variadic number of strings
Local(1)
For b@ = a@-1 To 0 Step -1 ' Reverse the hashes, load in array
@(b@) = Pop()
Next
For b@ = 0 To a@-1 ' Now call the appropriate subroutines
Proc @(b@)
Until b@ = a@-1
Print " "; ' Print a space
Next ' unless it is the last word
Print ' Terminate the string
Return
_Max Param(1) ' Calculate the maximum value
Local(3)
d@ = -(2^31) ' Set maximum to a tiny value
For b@ = 1 To a@ ' Get all values from the stack
c@ = Pop()
If c@ > d@ THEN d@ = c@ ' Change maximum if required
Next
Return (d@) ' Return the maximum
' Hashed labels
_Mary Print "Mary"; : Return
_had Print "had"; : Return
_a Print "a"; : Return
_little Print "little"; : Return
_lamb Print "lamb"; : Return</syntaxhighlight>
{{out}}
<pre>Mary had a little lamb
Maximum is: 19
0 OK, 0:236</pre>
=={{header|Unicon}}==
See [[#Icon|Icon]].
=={{header|Ursala}}==
<
#show+
main = f <'foo',12.5,('x','y'),100></
<code>f</code> is defined as a function that takes a list of any length of items of any type, and uses a built-in heuristic to decide how to print them. All functions in the language are polymorphic and variadic unless specifically restricted to the contrary.
Line 1,038 ⟶ 3,103:
('x','y')
100</pre>
=={{header|V}}==
Line 1,048 ⟶ 3,110:
Using a count as the indication of number of arguments to extract,
<
[zero? not] [swap puts pred]
while
].
100 200 300 400 500 3 myfn</
results in:
<
400
300</
=={{header|Visual Basic}}==
{{works with|Visual Basic|6}}
<syntaxhighlight lang="vb">Option Explicit
'--------------------------------------------------
Sub varargs(ParamArray a())
Dim n As Long, m As Long
Debug.Assert VarType(a) = (vbVariant Or vbArray)
For n = LBound(a) To UBound(a)
If IsArray(a(n)) Then
For m = LBound(a(n)) To UBound(a(n))
Debug.Print a(n)(m)
Next m
Else
Debug.Print a(n)
End If
Next
End Sub
'--------------------------------------------------
Sub Main()
Dim v As Variant
Debug.Print "call 1"
varargs 1, 2, 3
Debug.Print "call 2"
varargs 4, 5, 6, 7, 8
v = Array(9, 10, 11)
Debug.Print "call 3"
varargs v
ReDim v(0 To 2)
v(0) = 12
v(1) = 13
v(2) = 14
Debug.Print "call 4"
varargs 11, v
Debug.Print "call 5"
varargs v(2), v(1), v(0), 11
End Sub</syntaxhighlight>
{{out}}
<pre>call 1
1
2
3
call 2
4
5
6
7
8
call 3
9
10
11
call 4
11
12
13
14
call 5
14
13
12
11</pre>
=={{header|V (Vlang)}}==
<syntaxhighlight lang="v (vlang)">fn print_all(things ...string) {
for x in things {
println(x)
}
}</syntaxhighlight>
=={{header|Vorpal}}==
Each method can have a variable-length parameter (VPL), indicated by empty brackets after the parameter name. The VLP (if present) will be replaced with an array containing all the extra arguments passed to the method. Effectively, extra arguments are absorbed into the array. Calling the function with fewer parameters than needed is still a runtime error. The VPL may be omitted, which will result in an empty array as the value of that parameter.
<
x.print()
for(i = 0, i < y.size(), i = i + 1){
Line 1,081 ⟶ 3,210:
self.f(1, 2, 3, 4)
'---'.print()
self.f(1, 2)</
=={{header|Wren}}==
Wren doesn't support variadic functions and doesn't really need to as we can just write a function which takes one (or one more) argument and pass it a list.
<syntaxhighlight lang="wren">var printArgs = Fn.new { |args| args.each { |arg| System.print(arg) } }
printArgs.call(["Mary", "had", "3", "little", "lambs"])</syntaxhighlight>
{{out}}
<pre>
Mary
had
3
little
lambs
</pre>
=={{header|XLISP}}==
<syntaxhighlight lang="lisp">(defun print-on-separate-lines (&rest xs)
(for-each print xs))
; test the function:
(print-on-separate-lines 'i 'am 'doing 'a 'great 'work 'so 'that 'i 'cannot 'come 'down)
; to use it on a list of arguments assembled at run time, first create your list
(define test '(why should the work cease whilst i leave it and come down to you))
; and then call APPLY:
(apply print-on-separate-lines test)</syntaxhighlight>
{{out}}
<pre>I
AM
DOING
A
GREAT
WORK
SO
THAT
I
CANNOT
COME
DOWN
WHY
SHOULD
THE
WORK
CEASE
WHILST
I
LEAVE
IT
AND
COME
DOWN
TO
YOU</pre>
=={{header|XPL0}}==
Passing an array is probably a better way to accomplish this task.
<syntaxhighlight lang="xpl0">include c:\cxpl\codes; \intrinsic 'code' declarations
def IntSize=4; \number of bytes in an integer
proc Var(N...); \Display N strings passed as arguments
int N;
[N:= Reserve(N*IntSize); \reserve space for N string pointers
repeat Text(0,N(0)); CrLf(0); \display strings pointed to by N(0)
N:= N+IntSize; \point to next string
until N=GetHp; \pointing beyond reserved space?
];
Var(4, "Mary", "had", "a", "little")</syntaxhighlight>
Output:
<pre>
Mary
had
a
little
</pre>
=={{header|zkl}}==
In zkl, all functions and methods are variadic (they are just passed a list).
<syntaxhighlight lang="zkl">fcn f{vm.arglist.apply2("println")}
f("Mary","had","a","little");</syntaxhighlight>
{{output}}
<pre>
Mary
had
a
little
</pre>
<syntaxhighlight lang="zkl">a:="This is a test".split(); //-->L("This","is","a","test")
f(a.xplode()); // xplode takes a list and blows it apart into call args</syntaxhighlight>
{{output}}
<pre>
This
is
a
test
</pre>
<syntaxhighlight lang="zkl">fcn g{f(vm.pasteArgs(2)}
g(a.xplode());</syntaxhighlight>
pasteArgs takes the passed in function args and stuffs them back into the arglist of the function call
{{output}}
<pre>
a
test
</pre>
Of course, parameter lists can be named, have defaults, etc. Using the arglist, as a list, isn't the usual case.
{{omit from|GUISS}}
{{omit from|TI-89 BASIC}} <!-- No varargs -->
{{Omit from|ZX Spectrum Basic}} <!-- No varargs -->
{{omit from|OCaml}}
{{omit from|Axe}}
| |||