Conditional structures
AppleScript
if-then-else
if myVar is "ok" then return true
set i to 0 if i is 0 then return "zero" else if i mod 2 is 0 then return "even" else return "odd" end if
C
if-then-else
Compiler: GCC 4.1.2
int main (int argc, char ** argv) {
int input = 2;
if ( 3 == input ) {
// Do something
}
if ( 3 == input ) {
// Do something
} else {
// Do something else
}
}
switch
Compiler: GCC 4.1.2
int main (int argc, char ** argv) {
int input = 42;
switch (input) {
case 0:
// Do something, because input = 0
break;
case 1:
// Do something, because input = 1
break;
case 2:
// Do something, because input = 2
default:
// Do something else.
break; // Optional
}
}
C++
Run-Time Control Structures
if-then-else
Compiler: GCC 4.1.2
int main (void) {
int input = 2;
if ( 3 == input ) {
// Do something
}
if ( 3 == input ) {
// Do something
} else {
// Do something else
}
}
switch
Compiler: GCC 4.1.2
int main (void) {
int input = 42;
switch (input) {
case 0:
// Do something, because input = 0
break;
case 1:
// Do something, because input = 1
break;
case 2:
// Do something, because input = 2
// Because there is no 'break', we also fall through
// into the default case, executing it right after case 2:
default:
// Do something else.
break; // Optional
}
}
Compile-Time Control Structures
Preprocessor Techniques
- ifdef, #ifndef, etc..
ColdFusion
if-elseif-else
Compiler: ColdFusion any version
<cfif x eq 3> do something <cfelseif x eq 4> do something else <cfelse> do something else </cfif>
switch
Compiler: ColdFusion any version
<cfswitch expression="#x#"> <cfcase value="1"> do something </cfcase> <cfcase value="2"> do something </cfcase> <cfdefaultcase> do something </cfdefaultcase> </cfswitch>
Java
if-then-else
if(s.equals("Hello World"))
{
foo();
}
else if(s.equals("Bye World"))
{
bar();
}
else
{
deusEx();
}
ternary
s.equals("Hello World") ? foo : bar
switch
switch(c) {
case 'a':
foo();
break;
case 'b':
bar();
default:
foobar();
}
JavaScript
if-then-else
if(s=="Hello World")
{
foo();
}
else if(s=="Bye World")
{
bar();
}
else
{
deusEx();
}
OCaml
if-then-else
Compiler: OCaml 3.09
let condition = true if condition then ()//do something else ()//do something else
match-with
match expression with | 0 -> ()//do something | 1 -> ()//do something | n when n mod 2 = 0 -> ()//do something | _ -> ()//do something
Pascal
if-then-else
Compiler: Turbo Pascal 7.0
IF condition1 THEN
procedure1
ELSE
procedure3;
IF condition1 THEN
BEGIN
procedure1;
procedure2;
END
ELSE
procedure3;
IF condition 1 THEN
BEGIN
procedure1;
procedure2;
END
ELSE
BEGIN
procedure3;
procedure4;
END;
Perl
if-then-else
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
my $condition2 = 1;
if ( $condition1 ) {
# Do something
}
# post-conditional if
do_something() if $condition1;
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
my $condition2 = 1;
if ( $condition1 ) {
# Do something
} elsif ( $condition2 ) {
# Do somethine else
}
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
my $condition2 = 1;
if ( $condition1 ) {
# Do something
} else {
# Do something else
}
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
my $condition2 = 1;
if ( $condition1 ) {
# Do something
} elsif ( $condition2 ) {
# Do something else
} else {
# Do that other thing
}
($condition) ? print "Then\n" : print "Else\n"; # or my $var = ($condition) ? "Then" : "Else";
unless
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
my $condition1 = 0;
unless ( $condition1 ) {
# Do something
}
# post-conditional unless
do_something() unless $condition1;
unless ( $condition1 ) {
# Do something
} else {
# Do something else
}
switch
Interpreter: Perl 5.8.8
#!/usr/bin/perl -w
use strict;
use Switch;
$input = 42;
switch ($input) {
case 0 {
# Do something, because input = 0
}
case 1 {
# Do something, because input = 1
}
case "coffee" {
# Do something, because input = coffee
}
else {
# Do something else.
}
}
goto
Interpreter: Perl 5.8.8
Typically dispised by most Perl programmers
goto LABELB; LABELA: # note labels end with a colon not semi-colon goto END; LABELB: goto LABELA; END: exit(0);
PHP
if
Interpreter: PHP 3.x & 4.x & 5.x
<?php $foo = 3; if ($foo == 2) //do something if ($foo == 3) //do something else //do something else
if ($foo != 0)
{
//do something
}
else
{
//do another thing
}
?>
switch
Interpreter: PHP 3.x & 4.x & 5.x
<?php
switch ($i)
{
case "apple":
echo "i is apple";
break;
case "bar":
echo "i is bar";
break;
case "cake":
echo "i is cake";
break;
}
?>
Python
if-then-else
if x == 0:
foo()
elif x == 1:
bar()
elif x == 2:
baz()
else:
boz()
Ruby
if-then-else
if s == 'Hello World' foo elsif s == 'Bye World' bar else deus_ex end
case-when-else
case cartoon_character when 'Tom' chase when 'Jerry' flee else nil end
ternary
s == 'Hello World' ? foo : bar
SmallTalk
ifTrue/ifFalse
"Conditionals in Smalltalk are really messages sent to Boolean objects"
(( balance) > 0)
ifTrue: [Transcript cr; show: 'still sitting pretty!'.]
ifFalse: [Transcript cr; show: 'No money till payday!'.].
Visual Basic .NET
if-then-else
Basic
Dim result As String, a As String = "pants", b As String = "glasses" If a = b Then result = "passed" Else result = "failed" End If
Condensed
Dim result As String, a As String = "pants", b As String = "glasses" If a = b Then result = "passed" Else result = "failed" If a = b Then result = "passed" Else : result = "failed" End If If a = b Then : result = "passed" Else result = "failed" End If
if-then-elseif
Dim result As String, a As String = "pants", b As String = "glasses" If a = b Then result = "passed" ElseIf a <> b Then result = "failed" Else result = "impossible" End If
select-case-else
Dim result As String, a As String = "pants", b As String = "glasses"
Select Case a
Case b
result = "match"
Case a : result = "duh"
Case Else
result = "impossible"
End Select
inline-conditional
Imports Microsoft.VisualBasic
...
Dim result As String = CType(IIf("pants" = "glasses", "passed", "failed"), String)
generic-inline-conditional
Compiler: Microsoft (R) Visual Basic Compiler version 8.0
Imports Microsoft.VisualBasic
...
Function IIf2(Of T)(ByVal condition As Boolean, ByVal truepart As T, ByVal falsepart As T) As T
If condition Then Return truepart Else Return falsepart
End Function
...
Dim result As String = IIf2("pants" = "glasses", "passed", "failed") ' type is inferred