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Loops/Wrong ranges

From Rosetta Code


Task
Loops/Wrong ranges
You are encouraged to solve this task according to the task description, using any language you may know.

Some languages have syntax or function(s) to generate a range of numeric values from a start value, a stop value, and an increment.

The purpose of this task is to select the range syntax/function that would generate at least two increasing numbers when given a stop value more than the start value and a positive increment of less than half the difference.   You are then to use that same syntax/function but with different parameters; and show, here, what would happen.

Use these values if possible:

start stop increment Comment
-2 2 1 Normal
-2 2 0 Zero increment
-2 2 -1 Increments away from stop value
-2 2 10 First increment is beyond stop value
2 -2 1 Start more than stop: positive increment
2 2 1 Start equal stop: positive increment
2 2 -1 Start equal stop: negative increment
2 2 0 Start equal stop: zero increment
0 0 0 Start equal stop equal zero: zero increment
Related tasks



ALGOL W[edit]

Using the Algol W for loop and limiting the sequence to 10 values. The Algol W for loop considers the sign of the increment value when deciding whether to terminate when the loop counter exceeds the stop value (positive increment) or is smaller than the stop value (negative increment).

begin
 % sets the first n elements of s to the sequences of values specified by start, stop and increment  %
 % s( 0 ) is set to the number of elements of s that have been set, in case the sequence ends before n %
procedure sequence ( integer array s ( * )
 ; integer value n, start, stop, increment
) ;
begin
integer sPos;
for j := 0 until n do s( j ) := 0;
sPos  := 1;
for j := start step increment until stop do begin
if sPos > n then goto done;
s( sPos ) := j;
s( 0 ) := s( 0 ) + 1;
sPos  := sPos + 1;
end for_j ;
done:
end sequence ;
 % tests the sequence procedure %
procedure testSequence( integer value start, stop, increment
 ; string(48) value legend
) ;
begin
integer array s ( 0 :: 10 );
sequence( s, 10, start, stop, increment );
s_w := 0; % set output formating %
i_w := 4;
write( legend, ": " );
for i := 1 until s( 0 ) do writeon( s( i ) )
end testSequence ;
 % task trest cases %
testSequence( -2, 2, 1, "Normal" );
testSequence( -2, 2, 0, "Zero increment" );
testSequence( -2, 2, -1, "Increments away from stop value" );
testSequence( -2, 2, 10, "First increment is beyond stop value" );
testSequence( 2, -2, 1, "Start more than stop: positive increment" );
testSequence( 2, 2, 1, "Start equal stop: positive increment" );
testSequence( 2, 2, -1, "Start equal stop: negative increment" );
testSequence( 2, 2, 0, "Start equal stop: zero increment" );
testSequence( 0, 0, 0, "Start equal stop equal zero: zero increment" )
end.
Output:
Normal                                          :   -2  -1   0   1   2
Zero increment                                  :   -2  -2  -2  -2  -2  -2  -2  -2  -2  -2
Increments away from stop value                 :
First increment is beyond stop value            :   -2
Start more than stop: positive increment        :
Start equal stop: positive increment            :    2
Start equal stop: negative increment            :    2
Start equal stop: zero increment                :    2   2   2   2   2   2   2   2   2   2
Start equal stop equal zero: zero increment     :    0   0   0   0   0   0   0   0   0   0

AWK[edit]

 
# syntax: GAWK -f LOOPS_WRONG_RANGES.AWK
BEGIN {
arr[++n] = "-2, 2, 1,Normal"
arr[++n] = "-2, 2, 0,Zero increment"
arr[++n] = "-2, 2,-1,Increments away from stop value"
arr[++n] = "-2, 2,10,First increment is beyond stop value"
arr[++n] = " 2,-2, 1,Start more than stop: positive increment"
arr[++n] = " 2, 2, 1,Start equal stop: positive increment"
arr[++n] = " 2, 2,-1,Start equal stop: negative increment"
arr[++n] = " 2, 2, 0,Start equal stop: zero increment"
arr[++n] = " 0, 0, 0,Start equal stop equal zero: zero increment"
print("start,stop,increment,comment")
for (i=1; i<=n; i++) {
split(arr[i],A,",")
printf("%-52s : ",arr[i])
count = 0
for (j=A[1]; j<=A[2] && count<10; j+=A[3]) {
printf("%d ",j)
count++
}
printf("\n")
}
exit(0)
}
 
Output:
start,stop,increment,comment
-2, 2, 1,Normal                                      : -2 -1 0 1 2
-2, 2, 0,Zero increment                              : -2 -2 -2 -2 -2 -2 -2 -2 -2 -2
-2, 2,-1,Increments away from stop value             : -2 -3 -4 -5 -6 -7 -8 -9 -10 -11
-2, 2,10,First increment is beyond stop value        : -2
 2,-2, 1,Start more than stop: positive increment    :
 2, 2, 1,Start equal stop: positive increment        : 2
 2, 2,-1,Start equal stop: negative increment        : 2 1 0 -1 -2 -3 -4 -5 -6 -7
 2, 2, 0,Start equal stop: zero increment            : 2 2 2 2 2 2 2 2 2 2
 0, 0, 0,Start equal stop equal zero: zero increment : 0 0 0 0 0 0 0 0 0 0

C[edit]

C's 'for' statement appears to fit the bill here and so we use it directly to generate the required ranges of numbers though, as some of the ranges will be infinite, we limit the output to a maximum of 10 numbers.

#include <stdio.h>
 
#define TRUE 1
#define FALSE 0
 
typedef int bool;
 
typedef struct {
int start, stop, incr;
const char *comment;
} S;
 
S examples[9] = {
{-2, 2, 1, "Normal"},
{-2, 2, 0, "Zero increment"},
{-2, 2, -1, "Increments away from stop value"},
{-2, 2, 10, "First increment is beyond stop value"},
{2, -2, 1, "Start more than stop: positive increment"},
{2, 2, 1, "Start equal stop: positive increment"},
{2, 2, -1, "Start equal stop: negative increment"},
{2, 2, 0, "Start equal stop: zero increment"},
{0, 0, 0, "Start equal stop equal zero: zero increment"}
};
 
int main() {
int i, j, c;
bool empty;
S s;
const int limit = 10;
for (i = 0; i < 9; ++i) {
s = examples[i];
printf("%s\n", s.comment);
printf("Range(%d, %d, %d) -> [", s.start, s.stop, s.incr);
empty = TRUE;
for (j = s.start, c = 0; j <= s.stop && c < limit; j += s.incr, ++c) {
printf("%d ", j);
empty = FALSE;
}
if (!empty) printf("\b");
printf("]\n\n");
}
return 0;
}
Output:
Normal
Range(-2, 2, 1) -> [-2 -1 0 1 2]

Zero increment
Range(-2, 2, 0) -> [-2 -2 -2 -2 -2 -2 -2 -2 -2 -2]

Increments away from stop value
Range(-2, 2, -1) -> [-2 -3 -4 -5 -6 -7 -8 -9 -10 -11]

First increment is beyond stop value
Range(-2, 2, 10) -> [-2]

Start more than stop: positive increment
Range(2, -2, 1) -> []

Start equal stop: positive increment
Range(2, 2, 1) -> [2]

Start equal stop: negative increment
Range(2, 2, -1) -> [2 1 0 -1 -2 -3 -4 -5 -6 -7]

Start equal stop: zero increment
Range(2, 2, 0) -> [2 2 2 2 2 2 2 2 2 2]

Start equal stop equal zero: zero increment
Range(0, 0, 0) -> [0 0 0 0 0 0 0 0 0 0]

C#[edit]

Translation of: Visual Basic .NET

Behavior for naïve translation is different from VB.NET (and identical to C), as it does not handle an "overshot" iteration variable when the increment is negative.

using System;
using System.Collections.Generic;
 
static class Program
{
static void Main()
{
Example(-2, 2, 1, "Normal");
Example(-2, 2, 0, "Zero increment");
Example(-2, 2, -1, "Increments away from stop value");
Example(-2, 2, 10, "First increment is beyond stop value");
Example(2, -2, 1, "Start more than stop: positive increment");
Example(2, 2, 1, "Start equal stop: positive increment");
Example(2, 2, -1, "Start equal stop: negative increment");
Example(2, 2, 0, "Start equal stop: zero increment");
Example(0, 0, 0, "Start equal stop equal zero: zero increment");
}
 
static IEnumerable<int> Range(int start, int stop, int increment)
{
// To replicate the (arguably more correct) behavior of VB.NET:
//for (int i = start; increment >= 0 ? i <= stop : stop <= i; i += increment)
 
// Decompiling the IL emitted by the VB compiler (uses shifting right by 31 as the signum function and bitwise xor in place of the conditional expression):
//for (int i = start; ((increment >> 31) ^ i) <= ((increment >> 31) ^ stop); i += increment)
 
// "Naïve" translation.
for (int i = start; i <= stop; i += increment)
yield return i;
}
 
static void Example(int start, int stop, int increment, string comment)
{
// Add a space, pad to length 50 with hyphens, and add another space.
Console.Write((comment + " ").PadRight(50, '-') + " ");
 
const int MAX_ITER = 9;
 
int iteration = 0;
foreach (int i in Range(start, stop, increment))
{
Console.Write("{0,2} ", i);
 
if (++iteration > MAX_ITER) break;
}
 
Console.WriteLine();
}
}
Output (identical to C):
Normal ------------------------------------------- -2 -1  0  1  2
Zero increment ----------------------------------- -2 -2 -2 -2 -2 -2 -2 -2 -2 -2
Increments away from stop value ------------------ -2 -3 -4 -5 -6 -7 -8 -9 -10 -11
First increment is beyond stop value ------------- -2
Start more than stop: positive increment ---------
Start equal stop: positive increment -------------  2
Start equal stop: negative increment -------------  2  1  0 -1 -2 -3 -4 -5 -6 -7
Start equal stop: zero increment -----------------  2  2  2  2  2  2  2  2  2  2
Start equal stop equal zero: zero increment ------  0  0  0  0  0  0  0  0  0  0

C translation[edit]

Translation of: C (old version)

Just for fun; some strictly unnecessary changes made to be closer to idiomatic C#.

using System;
 
static class Program {
struct S {
public int Start, Stop, Incr;
public string Comment;
}
 
static readonly S[] examples = {
new S{Start=-2, Stop=2, Incr=1, Comment="Normal"},
new S{Start=-2, Stop=2, Incr=0, Comment="Zero increment"},
new S{Start=-2, Stop=2, Incr=-1, Comment="Increments away from stop value"},
new S{Start=-2, Stop=2, Incr=10, Comment="First increment is beyond stop value"},
new S{Start=2, Stop=-2, Incr=1, Comment="Start more than stop: positive increment"},
new S{Start=2, Stop=2, Incr=1, Comment="Start equal stop: positive increment"},
new S{Start=2, Stop=2, Incr=-1, Comment="Start equal stop: negative increment"},
new S{Start=2, Stop=2, Incr=0, Comment="Start equal stop: zero increment"},
new S{Start=0, Stop=0, Incr=0, Comment="Start equal stop equal zero: zero increment"}
};
 
static int Main() {
const int limit = 10;
bool empty;
for (int i = 0; i < 9; ++i) {
S s = examples[i];
Console.Write("{0}\n", s.Comment);
Console.Write("Range({0:d}, {1:d}, {2:d}) -> [", s.Start, s.Stop, s.Incr);
empty = true;
for (int j = s.Start, c = 0; j <= s.Stop && c < limit; j += s.Incr, ++c) {
Console.Write("{0:d} ", j);
empty = false;
}
if (!empty) Console.Write("\b");
Console.Write("]\n\n");
}
return 0;
}
}
Output:

Same as original C.

Common Lisp[edit]

 
(dolist (lst '((-2 2 1 "Normal") ; Iterate the parameters list `start' `stop' `increment' and `comment'
(-2 2 0 "Zero increment")
(-2 2 -1 "Increments away from stop value")
(-2 2 10 "First increment is beyond stop value")
( 2 -2 1 "Start more than stop: positive increment")
( 2 2 1 "Start equal stop: positive increment")
( 2 2 -1 "Start equal stop: negative increment")
( 2 2 0 "Start equal stop: zero increment")
( 0 0 0 "Start equal stop equal zero: zero increment")))
(do ((i (car lst) (incf i (caddr lst))) ; Initialize `start' and set `increment'
(result ()) ; Initialize the result list
(loop-max 0 (incf loop-max))) ; Initialize a loop limit
((or (> i (cadr lst)) ; Break condition to `stop'
(> loop-max 10)) ; Break condition to loop limit
(format t "~&~44a: ~{~3d ~}" ; Finally print
(cadddr lst) ; The `comment'
(reverse result))) ; The in(de)creased numbers into result
(push i result))) ; Add the number to result
 
Output:
Normal                                      :  -2  -1   0   1   2 
Zero increment                              :  -2  -2  -2  -2  -2  -2  -2  -2  -2  -2  -2 
Increments away from stop value             :  -2  -3  -4  -5  -6  -7  -8  -9 -10 -11 -12 
First increment is beyond stop value        :  -2 
Start more than stop: positive increment    : 
Start equal stop: positive increment        :   2 
Start equal stop: negative increment        :   2   1   0  -1  -2  -3  -4  -5  -6  -7  -8 
Start equal stop: zero increment            :   2   2   2   2   2   2   2   2   2   2   2 
Start equal stop equal zero: zero increment :   0   0   0   0   0   0   0   0   0   0   0 

Delphi[edit]

 
program Wrong_ranges;
 
{$APPTYPE CONSOLE}
 
uses
System.SysUtils;
 
procedure Example(start, stop, Increment: Integer; comment: string);
var
MAX_ITER, iteration, i: Integer;
begin
Write((comment + ' ').PadRight(50, '-') + ' ');
MAX_ITER := 9;
iteration := 0;
 
if Increment = 1 then
begin
for i := start to stop do
begin
Write(i: 2, ' ');
inc(iteration);
if iteration >= MAX_ITER then
Break;
end;
Writeln;
exit;
end;
 
if Increment = -1 then
begin
for i := start downto stop do
begin
Write(i: 2, ' ');
inc(iteration);
if iteration >= MAX_ITER then
Break;
end;
Writeln;
exit;
end;
 
Writeln('Not supported');
end;
 
begin
Example(-2, 2, 1, 'Normal');
Example(-2, 2, 0, 'Zero increment');
Example(-2, 2, -1, 'Increments away from stop value');
Example(-2, 2, 10, 'First increment is beyond stop value');
Example(2, -2, 1, 'Start more than stop: positive increment');
Example(2, 2, 1, 'Start equal stop: positive increment');
Example(2, 2, -1, 'Start equal stop: negative increment');
Example(2, 2, 0, 'Start equal stop: zero increment');
Example(0, 0, 0, 'Start equal stop equal zero: zero increment');
Readln;
end.
Output:
Normal ------------------------------------------- -2 -1  0  1  2
Zero increment ----------------------------------- Not supported
Increments away from stop value ------------------
First increment is beyond stop value ------------- Not supported
Start more than stop: positive increment ---------
Start equal stop: positive increment -------------  2
Start equal stop: negative increment -------------  2
Start equal stop: zero increment ----------------- Not supported
Start equal stop equal zero: zero increment ------ Not supported

Version with TEnumerate:

 
program Wrong_rangesEnumerator;
 
{$APPTYPE CONSOLE}
 
uses
System.SysUtils;
 
type
TRange = record
private
Fincrement: Integer;
FIndex: Integer;
FStart, FStop, FValue: Integer;
function GetCurrent: Integer; inline;
public
constructor Create(start, stop, Increment: Integer);
function MoveNext: Boolean; inline;
function GetEnumerator: TRange;
property Current: Integer read GetCurrent;
end;
 
{ TEnumerator<T> }
 
constructor TRange.Create(start, stop, Increment: Integer);
begin
FStart := start;
FStop := stop;
Fincrement := Increment;
FValue := start - Increment;
end;
 
function TRange.GetCurrent: Integer;
begin
Result := FValue;
end;
 
function TRange.GetEnumerator: TRange;
begin
Result := self;
end;
 
function TRange.MoveNext: Boolean;
begin
FValue := FValue + Fincrement;
if (Fincrement > 0) and (FValue > FStop) then
exit(False);
 
if (Fincrement < 0) and (FValue < FStop) then
exit(False);
 
Result := True;
end;
 
procedure Example(start, stop, Increment: Integer; comment: string);
var
MAX_ITER, iteration, i, e: Integer;
begin
Write((comment + ' ').PadRight(50, '-') + ' ');
MAX_ITER := 9;
iteration := 0;
 
for e in TRange.Create(start, stop, Increment) do
begin
Write(e: 2, ' ');
inc(iteration);
if iteration >= MAX_ITER then
Break;
end;
 
Writeln;
end;
 
begin
Example(-2, 2, 1, 'Normal');
Example(-2, 2, 0, 'Zero increment');
Example(-2, 2, -1, 'Increments away from stop value');
Example(-2, 2, 10, 'First increment is beyond stop value');
Example(2, -2, 1, 'Start more than stop: positive increment');
Example(2, 2, 1, 'Start equal stop: positive increment');
Example(2, 2, -1, 'Start equal stop: negative increment');
Example(2, 2, 0, 'Start equal stop: zero increment');
Example(0, 0, 0, 'Start equal stop equal zero: zero increment');
Readln;
end.
Output:
Normal ------------------------------------------- -2 -1  0  1  2
Zero increment ----------------------------------- -2 -2 -2 -2 -2 -2 -2 -2 -2
Increments away from stop value ------------------
First increment is beyond stop value ------------- -2
Start more than stop: positive increment ---------
Start equal stop: positive increment -------------  2
Start equal stop: negative increment -------------  2
Start equal stop: zero increment -----------------  2  2  2  2  2  2  2  2  2
Start equal stop equal zero: zero increment ------  0  0  0  0  0  0  0  0  0

Factor[edit]

<range> divides by the step value, so a step of 0 causes a divide by zero exception. For the purpose of getting through all the examples, the exceptions are dropped and execution continues, which in general should be avoided.

USING: continuations formatting io kernel math.ranges
prettyprint sequences ;
 
: try-range ( from length step -- )
[ <range> { } like . ]
[ 4drop "Exception: divide by zero." print ] recover ;
 
{
{ -2 2 1 } { 2 2 0 } { -2 2 -1 } { -2 2 10 } { 2 -2 1 }
{ 2 2 1 } { 2 2 -1 } { 2 2 0 } { 0 0 0 }
}
[
first3
[ "%2d %2d %2d <range> => " printf ]
[ try-range ] 3bi
] each
Output:
-2  2  1 <range>  =>  { -2 -1 0 1 2 }
 2  2  0 <range>  =>  Exception: divide by zero.
-2  2 -1 <range>  =>  { }
-2  2 10 <range>  =>  { -2 }
 2 -2  1 <range>  =>  { }
 2  2  1 <range>  =>  { 2 }
 2  2 -1 <range>  =>  { 2 }
 2  2  0 <range>  =>  Exception: divide by zero.
 0  0  0 <range>  =>  Exception: divide by zero.

Forth[edit]

Works with: gforth version 0.7.3

Forth, being a language that assumes a smart programmer, has absolutely no qualms with integer overflow or zero increments; it simply does what you told it to, not what you meant. This is, of course, dangerous code, so another looping construct is provided that does check whether the bounds and increment are valid.

DO[edit]

: test-seq  ( start stop inc -- )
cr rot dup ." start: " 2 .r
rot dup ." stop: " 2 .r
rot dup ." inc: " 2 .r ." | "
-rot swap do i . dup +loop drop ;
-2 2 1 test-seq
-2 2 0 test-seq
-2 2 -1 test-seq
-2 2 10 test-seq
2 -2 1 test-seq
2 2 1 test-seq
2 2 -1 test-seq
2 2 0 test-seq
0 0 0 test-seq
Output:

Some of these loop infinitely, and some under/overflow, so for the sake of brevity long outputs will be truncated by ....

start: -2 stop:  2 inc:  1 | -2 -1 0 1
start: -2 stop:  2 inc:  0 | -2 -2 -2 -2 -2 ...
start: -2 stop:  2 inc: -1 | -2 -3 -4 -5 ... 5 4 3 2
start: -2 stop:  2 inc: 10 | -2
start:  2 stop: -2 inc:  1 | 2 3 4 5 ... -6 -5 -4 -3
start:  2 stop:  2 inc:  1 | 2 3 4 5 ... -2 -1 0 1
start:  2 stop:  2 inc: -1 | 2
start:  2 stop:  2 inc:  0 | 2 2 2 2 2 ...
start:  0 stop:  0 inc:  0 | 0 0 0 0 0 ...

?DO[edit]

This is almost exactly the same as the above DO, but the bounds are checked for validity first.

: test-seq  ( start stop inc -- )
cr rot dup ." start: " 2 .r
rot dup ." stop: " 2 .r
rot dup ." inc: " 2 .r ." | "
-rot swap ?do i . dup +loop drop ;
-2 2 1 test-seq
-2 2 0 test-seq
-2 2 -1 test-seq
-2 2 10 test-seq
2 -2 1 test-seq
2 2 1 test-seq
2 2 -1 test-seq
2 2 0 test-seq
0 0 0 test-seq
Output:

Some of these loop infinitely, and some under/overflow, so for the sake of brevity long outputs will be truncated by .... If there is no output beyond the | symbol, then the loop was not entered.

start: -2 stop:  2 inc:  1 | -2 -1 0 1
start: -2 stop:  2 inc:  0 | -2 -2 -2 -2 -2 ...
start: -2 stop:  2 inc: -1 | -2 -3 -4 -5 ... 5 4 3 2
start: -2 stop:  2 inc: 10 | -2
start:  2 stop: -2 inc:  1 | 2 3 4 5 ... -6 -5 -4 -3
start:  2 stop:  2 inc:  1 |
start:  2 stop:  2 inc: -1 |
start:  2 stop:  2 inc:  0 |
start:  0 stop:  0 inc:  0 |

FreeBASIC[edit]

data -2,2,1,"Normal",-2,2,0,"Zero increment",-2,2,-1,"Increments away from stop value"
data -2,2,10,"First increment is beyond stop value",2,-2,1,"Start more than stop: positive increment"
data 2,2,1,"Start equal stop: positive increment",2,2,-1,"Start equal stop: negative increment"
data 2,2,0,"Start equal stop: zero increment",0,0,0,"Start equal stop equal zero: zero increment"
 
dim as integer i, start, fin, inc, vr, count
dim as string cmt
for i = 1 to 9
count = 0
read start, fin, inc, cmt
print cmt
print using " Looping from ### to ### in increments of ##"; start; fin; inc
for vr = start to fin step inc
print " Loop index = ",vr
count += 1
if count = 10 then
print " Breaking infinite loop"
exit for
end if
next vr
print " Loop finished"
print
print
next i
 
Output:
Normal
  Looping from  -2 to   2 in increments of  1
        Loop index =        -2
        Loop index =        -1
        Loop index =         0
        Loop index =         1
        Loop index =         2
  Loop finished


Zero increment
  Looping from  -2 to   2 in increments of  0
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Loop index =        -2
        Breaking infinite loop
  Loop finished


Increments away from stop value
  Looping from  -2 to   2 in increments of -1
  Loop finished


First increment is beyond stop value
  Looping from  -2 to   2 in increments of 10
        Loop index =        -2
  Loop finished


Start more than stop: positive increment
  Looping from   2 to  -2 in increments of  1
  Loop finished


Start equal stop: positive increment
  Looping from   2 to   2 in increments of  1
        Loop index =         2
  Loop finished


Start equal stop: negative increment
  Looping from   2 to   2 in increments of -1
        Loop index =         2
  Loop finished


Start equal stop: zero increment
  Looping from   2 to   2 in increments of  0
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Loop index =         2
        Breaking infinite loop
  Loop finished


Start equal stop equal zero: zero increment
  Looping from   0 to   0 in increments of  0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Loop index =         0
        Breaking infinite loop
  Loop finished

Go[edit]

Go has only one loop, a 'for' statement, which supports four different syntactical forms commonly found in other C-family languages:

1. A C-like 'for' loop with initialization, condition and increment sections.

2. The 'while' loop functionality (condition only)

3. Infinite loop, equivalent to for(;;) (all sections omitted)

4. Looping over a range of values, similar to foreach etc. (using 'range' keyword).

It appears that either #1 or #4 fits the requirements of this task so I've written a function which generates the appropriate sequence using #1 (limited to a maximum of 10 elements as some sequences will be infinite). I've then applied #4 to the resulting sequence. All sequences include the stop value if it's actually reached.

package main
 
import "fmt"
 
type S struct {
start, stop, incr int
comment string
}
 
var examples = []S{
{-2, 2, 1, "Normal"},
{-2, 2, 0, "Zero increment"},
{-2, 2, -1, "Increments away from stop value"},
{-2, 2, 10, "First increment is beyond stop value"},
{2, -2, 1, "Start more than stop: positive increment"},
{2, 2, 1, "Start equal stop: positive increment"},
{2, 2, -1, "Start equal stop: negative increment"},
{2, 2, 0, "Start equal stop: zero increment"},
{0, 0, 0, "Start equal stop equal zero: zero increment"},
}
 
func sequence(s S, limit int) []int {
var seq []int
for i, c := s.start, 0; i <= s.stop && c < limit; i, c = i+s.incr, c+1 {
seq = append(seq, i)
}
return seq
}
 
func main() {
const limit = 10
for _, ex := range examples {
fmt.Println(ex.comment)
fmt.Printf("Range(%d, %d, %d) -> ", ex.start, ex.stop, ex.incr)
fmt.Println(sequence(ex, limit))
fmt.Println()
}
}
Output:
Normal
Range(-2, 2, 1) -> [-2 -1 0 1 2]

Zero increment
Range(-2, 2, 0) -> [-2 -2 -2 -2 -2 -2 -2 -2 -2 -2]

Increments away from stop value
Range(-2, 2, -1) -> [-2 -3 -4 -5 -6 -7 -8 -9 -10 -11]

First increment is beyond stop value
Range(-2, 2, 10) -> [-2]

Start more than stop: positive increment
Range(2, -2, 1) -> []

Start equal stop: positive increment
Range(2, 2, 1) -> [2]

Start equal stop: negative increment
Range(2, 2, -1) -> [2 1 0 -1 -2 -3 -4 -5 -6 -7]

Start equal stop: zero increment
Range(2, 2, 0) -> [2 2 2 2 2 2 2 2 2 2]

Start equal stop equal zero: zero increment
Range(0, 0, 0) -> [0 0 0 0 0 0 0 0 0 0]

Haskell[edit]

import Data.List
 
main = putStrLn $ showTable True '|' '-' '+' table
 
table = [["start","stop","increment","Comment","Code","Result/Analysis"]
,["-2","2","1","Normal","[-2,-1..2] or [-2..2]",show [-2,-1..2]]
,["-2","2","0","Zero increment","[-2,-2..2]","Infinite loop of -2 <=> repeat -2"]
,["-2","2","-1","Increments away from stop value","[-2,-3..2]",show [-2,-3..2]]
,["-2","2","10","First increment is beyond stop value","[-2,8..2]",show [-2,8..2]]
,["2","-2","1","Start more than stop: positive increment","[2,3.. -2]",show [2,3.. -2]]
,["2","2","1","Start equal stop: positive increment","[2,3..2]",show [2,3..2]]
,["2","2","-1","Start equal stop: negative increment","[2,1..2]",show [2,1..2]]
,["2","2","0","Start equal stop: zero increment","[2,2..2]","Infinite loop of 2 <=> repeat 2"]
,["0","0","0","Start equal stop equal zero: zero increment","[0,0..0]", "Infinite loop of 0 <=> repeat 0"]]
 
showTable::Bool -> Char -> Char -> Char -> [[String]] -> String
showTable _ _ _ _ [] = []
showTable header ver hor sep contents = unlines $ hr:(if header then z:hr:zs else intersperse hr zss) ++ [hr]
where
vss = map (map length) $ contents
ms = map maximum $ transpose vss ::[Int]
hr = concatMap (\ n -> sep : replicate n hor) ms ++ [sep]
top = replicate (length hr) hor
bss = map (\ps -> map (flip replicate ' ') $ zipWith (-) ms ps) $ vss
zss@(z:zs) = zipWith (\us bs -> (concat $ zipWith (\x y -> (ver:x) ++ y) us bs) ++ [ver]) contents bss
Output:
+-----+----+---------+-------------------------------------------+---------------------+---------------------------------+
|start|stop|increment|Comment                                    |Code                 |Result/Analysis                  |
+-----+----+---------+-------------------------------------------+---------------------+---------------------------------+
|-2   |2   |1        |Normal                                     |[-2,-1..2] or [-2..2]|[-2,-1,0,1,2]                    |
|-2   |2   |0        |Zero increment                             |[-2,-2..2]           |Infinite loop of -2 <=> repeat -2|
|-2   |2   |-1       |Increments away from stop value            |[-2,-3..2]           |[]                               |
|-2   |2   |10       |First increment is beyond stop value       |[-2,8..2]            |[-2]                             |
|2    |-2  |1        |Start more than stop: positive increment   |[2,3.. -2]           |[]                               |
|2    |2   |1        |Start equal stop: positive increment       |[2,3..2]             |[2]                              |
|2    |2   |-1       |Start equal stop: negative increment       |[2,1..2]             |[2]                              |
|2    |2   |0        |Start equal stop: zero increment           |[2,2..2]             |Infinite loop of 2 <=> repeat 2  |
|0    |0   |0        |Start equal stop equal zero: zero increment|[0,0..0]             |Infinite loop of 0 <=> repeat 0  |
+-----+----+---------+-------------------------------------------+---------------------+---------------------------------+

Huginn[edit]

Huginn has the Range generator in Algorithms package. Instantiation of an a priori invalid range is a fatal error.

import Algorithms as algo;
 
class Example {
_start = none;
_stop = none;
_step = none;
_comment = none;
}
 
main() {
examples = [
Example( -2, 2, 1, "Normal" ),
Example( 2, 2, 0, "Start equal stop: zero increment" ),
Example( 0, 0, 0, "Start equal stop equal zero: zero increment" ),
Example( 2, 2, 1, "Start equal stop: positive increment" ),
Example( 2, 2, -1, "Start equal stop: negative increment" ),
Example( -2, 2, 10, "First increment is beyond stop value" ),
Example( -2, 2, 0, "Zero increment, stop greater than start" ),
Example( -2, 2, -1, "Increments away from stop value" ),
Example( 2, -2, 1, "Start more than stop: positive increment" )
];
for ( ex : examples ) {
print(
"{}\nRange( {}, {}, {} ) -> ".format(
ex._comment, ex._start, ex._stop, ex._step
)
);
r = algo.range( ex._start, ex._stop, ex._step );
print(
"{}\n\n".format(
algo.materialize( algo.slice( r, 22 ), list )
)
);
}
}
Output:
Normal
Range( -2, 2, 1 ) -> [-2, -1, 0, 1]

Start equal stop: zero increment
Range( 2, 2, 0 ) -> []

Start equal stop equal zero: zero increment
Range( 0, 0, 0 ) -> []

Start equal stop: positive increment
Range( 2, 2, 1 ) -> []

Start equal stop: negative increment
Range( 2, 2, -1 ) -> []

First increment is beyond stop value
Range( -2, 2, 10 ) -> [-2]

Zero increment, stop greater than start
Range( -2, 2, 0 ) -> ./range.hgn:32:17: Invalid range.
Exit 3

J[edit]

J can build ranges.

   NB. rank 3 integers with a bit of inversion
   i. 2 _3 6
12 13 14 15 16 17
 6  7  8  9 10 11
 0  1  2  3  4  5

30 31 32 33 34 35
24 25 26 27 28 29
18 19 20 21 22 23


   NB. from _3 to 3 in 12 steps
   i: 3j12
_3 _2.5 _2 _1.5 _1 _0.5 0 0.5 1 1.5 2 2.5 3

The loops with multiple ranges shall use this version of range. Or so it is in on 2019, March 6. http://rosettacode.org/wiki/Loops/with_multiple_ranges#J

R =: ".;._2 [ 0 : 0
    9      2      _2   NB. valid descending range
   _2      2       1   NB. valid ascending range
   _2      2       0
   _2      2       _1
   _2      2       10
   2       _2      1
   2       2       1
   2       2       _1
   2       2       0
   0       0       0
)

NB. define range as a linear polynomial
start =: 0&{
stop =: 1&{
increment =: 2&{ :: 1:  NB. on error use 1
range =: (start , increment) p. [: i. [: >: [: <. (stop - start) % increment

   NB. the first two of these are ranges with valid arguments
   (; range :: ('*error*'"_))"1 R
+-------+-----------+
|9 2 _2 |9 7 5 3    |
+-------+-----------+
|_2 2 1 |_2 _1 0 1 2|
+-------+-----------+
|_2 2 0 |*error*    |
+-------+-----------+
|_2 2 _1|_4 _3 _2   |
+-------+-----------+
|_2 2 10|_2         |
+-------+-----------+
|2 _2 1 |4 3 2      |
+-------+-----------+
|2 2 1  |2          |
+-------+-----------+
|2 2 _1 |2          |
+-------+-----------+
|2 2 0  |2          |
+-------+-----------+
|0 0 0  |0          |
+-------+-----------+

Java[edit]

 
import java.util.ArrayList;
import java.util.List;
 
public class LoopsWrongRanges {
 
public static void main(String[] args) {
runTest(new LoopTest(-2, 2, 1, "Normal"));
runTest(new LoopTest(-2, 2, 0, "Zero increment"));
runTest(new LoopTest(-2, 2, -1, "Increments away from stop value"));
runTest(new LoopTest(-2, 2, 10, "First increment is beyond stop value"));
runTest(new LoopTest(2, -2, 1, "Start more than stop: positive increment"));
runTest(new LoopTest(2, 2, 1, "Start equal stop: positive increment"));
runTest(new LoopTest(2, 2, -1, "Start equal stop: negative increment"));
runTest(new LoopTest(2, 2, 0, "Start equal stop: zero increment"));
runTest(new LoopTest(0, 0, 0, "Start equal stop equal zero: zero increment"));
}
 
private static void runTest(LoopTest loopTest) {
List<Integer> values = new ArrayList<>();
for (int i = loopTest.start ; i <= loopTest.stop ; i += loopTest.increment ) {
values.add(i);
if ( values.size() >= 10 ) {
break;
}
}
System.out.printf("%-45s %s%s%n", loopTest.comment, values, values.size()==10 ? " (loops forever)" : "");
}
 
private static class LoopTest {
int start;
int stop;
int increment;
String comment;
public LoopTest(int start, int stop, int increment, String comment) {
this.start = start;
this.stop = stop;
this.increment = increment;
this.comment = comment;
}
}
 
}
 
Output:
Normal                                        [-2, -1, 0, 1, 2]
Zero increment                                [-2, -2, -2, -2, -2, -2, -2, -2, -2, -2] (loops forever)
Increments away from stop value               [-2, -3, -4, -5, -6, -7, -8, -9, -10, -11] (loops forever)
First increment is beyond stop value          [-2]
Start more than stop: positive increment      []
Start equal stop: positive increment          [2]
Start equal stop: negative increment          [2, 1, 0, -1, -2, -3, -4, -5, -6, -7] (loops forever)
Start equal stop: zero increment              [2, 2, 2, 2, 2, 2, 2, 2, 2, 2] (loops forever)
Start equal stop equal zero: zero increment   [0, 0, 0, 0, 0, 0, 0, 0, 0, 0] (loops forever)

Julia[edit]

Julia has a start:increment:stop iterator syntax, which allows negative increments, but not zero increments.

 
collect(-2:1:2) # → [-2, -1, 0, 1, 2]
collect(-2:0:2) # fails
collect(-2:-1:2) # → []
collect(-2:10:2) # → [-2]
collect(2:1:-2) # → []
collect(2:1:2) # → [2]
collect(2:-1:2) # → [2]
collect(2:0:2) # fails
collect(0:0:0) # fails
 

Kotlin[edit]

Although Kotlin's 'for' statement can deal with a range of integers, the increment must be positive and so it cannot be used for this task. We therefore use instead a 'while' statement to generate the same sequence as a C language 'for' statement would (limited to a maximum of 10 elements as some sequences will be infinite) and wrap it in a function.

// Version 1.2.70
 
class Example(val start: Int, val stop: Int, val incr: Int, val comment: String)
 
var examples = listOf(
Example(-2, 2, 1, "Normal"),
Example(-2, 2, 0, "Zero increment"),
Example(-2, 2, -1, "Increments away from stop value"),
Example(-2, 2, 10, "First increment is beyond stop value"),
Example(2, -2, 1, "Start more than stop: positive increment"),
Example(2, 2, 1, "Start equal stop: positive increment"),
Example(2, 2, -1, "Start equal stop: negative increment"),
Example(2, 2, 0, "Start equal stop: zero increment"),
Example(0, 0, 0, "Start equal stop equal zero: zero increment")
)
 
fun sequence(ex: Example, limit: Int) =
if (ex.incr == 0) {
List(limit) { ex.start }
}
else {
val res = mutableListOf<Int>()
var c = 0
var i = ex.start
while (i <= ex.stop && c < limit) {
res.add(i)
i += ex.incr
c++
}
res
}
 
fun main(args: Array<String>) {
for (ex in examples) {
println(ex.comment)
System.out.printf("Range(%d, %d, %d) -> ", ex.start, ex.stop, ex.incr)
println(sequence(ex, 10))
println()
}
}
Output:
Normal
Range(-2, 2, 1) -> [-2, -1, 0, 1, 2]

Zero increment
Range(-2, 2, 0) -> [-2, -2, -2, -2, -2, -2, -2, -2, -2, -2]

Increments away from stop value
Range(-2, 2, -1) -> [-2, -3, -4, -5, -6, -7, -8, -9, -10, -11]

First increment is beyond stop value
Range(-2, 2, 10) -> [-2]

Start more than stop: positive increment
Range(2, -2, 1) -> []

Start equal stop: positive increment
Range(2, 2, 1) -> [2]

Start equal stop: negative increment
Range(2, 2, -1) -> [2, 1, 0, -1, -2, -3, -4, -5, -6, -7]

Start equal stop: zero increment
Range(2, 2, 0) -> [2, 2, 2, 2, 2, 2, 2, 2, 2, 2]

Start equal stop equal zero: zero increment
Range(0, 0, 0) -> [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

langur[edit]

Langur has series() and pseries() functions, which generate arrays. These are not limited to integers for start, stop, or increment values. The pseries() function never returns a descending series (returns empty array instead).

You don't always have to convert a range to a series explicitly. Since 0.6.15, the functions map(), fold(), foldfrom(), and zip() accept ranges in place of arrays.

In the following example, we could have just started with an array of arrays, but following the Python example, we process the .data string into a table.

Translation of: Python
Works with: langur version 0.10

Langur 0.7.0 changed the implicit exception variable from .err to _err, and 0.7.1 allows you to map to multiple functions.

Prior to 0.10, multi-variable declaration/assignment would use parentheses around the variable names (.start, .stop, .inc, .comment).

val .data = q:block END
start stop increment comment
-2 2 1 Normal
-2 2 0 Zero increment
-2 2 -1 Increments away from stop value
-2 2 10 First increment is beyond stop value
2 -2 1 Start more than stop: positive increment
2 2 1 Start equal stop: positive increment
2 2 -1 Start equal stop: negative increment
2 2 0 Start equal stop: zero increment
0 0 0 Start equal stop equal zero: zero increment
END
 
var .table = submatches(RE/([^ ]+) +([^ ]+) +([^ ]+) +(.+)\n?/, .data)
val .f = toNumber
for .i in 2..len(.table) {
.table[.i] = map [.f, .f, .f, _], .table[.i]
}
 
for .test in rest(.table) {
val .start, .stop, .inc, .comment = .test
{
val .series = series(.start to .stop, .inc)
catch {
writeln $"\.comment;\nERROR: \._err["msg"]:L200(...);\n"
} else {
writeln $"\.comment;\nresult: \.series;\n"
}
}
}
Output:
Normal
result: [-2, -1, 0, 1, 2]

Zero increment
result: []

Increments away from stop value
ERROR: Expected ascending range with positive increment, or descending range with negative increment

First increment is beyond stop value
result: [-2]

Start more than stop: positive increment
ERROR: Expected ascending range with positive increment, or descending range with negative increment

Start equal stop: positive increment
result: [2]

Start equal stop: negative increment
result: [2]

Start equal stop: zero increment
result: []

Start equal stop equal zero: zero increment
result: []

Perl[edit]

None of these sequences are 'errors', though some are of infinite length, and #5 has a length of zero.

for $i (
[ -2, 2, 1], #1 Normal
[ -2, 2, 0], #2 Zero increment
[ -2, 2, -1], #3 Increments away from stop value
[ -2, 2, 10], #4 First increment is beyond stop value
[ 2, -2, 1], #5 Start more than stop: positive increment
[ 2, 2, 1], #6 Start equal stop: positive increment
[ 2, 2, -1], #7 Start equal stop: negative increment
[ 2, 2, 0], #8 Start equal stop: zero increment
[ 0, 0, 0], #9 Start equal stop equal zero: zero increment
) {
$iter = gen_seq(@$i);
printf "start: %3d stop: %3d incr: %3d | ", @$i;
printf "%4s", &$iter for 1..10;
print "\n";
}
 
sub gen_seq {
my($start,$stop,$increment) = @_;
$n = 0;
return sub {
$term = $start + $n++ * $increment;
return $term > $stop ? '' : $term;
}
}
Output:
start:  -2  stop:   2  incr:   1 |   -2  -1   0   1   2
start:  -2  stop:   2  incr:   0 |   -2  -2  -2  -2  -2  -2  -2  -2  -2  -2
start:  -2  stop:   2  incr:  -1 |   -2  -3  -4  -5  -6  -7  -8  -9 -10 -11
start:  -2  stop:   2  incr:  10 |   -2
start:   2  stop:  -2  incr:   1 |
start:   2  stop:   2  incr:   1 |    2
start:   2  stop:   2  incr:  -1 |    2   1   0  -1  -2  -3  -4  -5  -6  -7
start:   2  stop:   2  incr:   0 |    2   2   2   2   2   2   2   2   2   2
start:   0  stop:   0  incr:   0 |    0   0   0   0   0   0   0   0   0   0

Phix[edit]

Phix for loops do not allow a zero step (neither are any floating point values permitted).
The following shows the behaviour of both for and while loops, and the latter has a couple of additional commented out termination checks that might be appropriate in some cases.

procedure test(integer start, stop, step, string legend, bool bFor)
sequence res = {}
if bFor then
try
for i=start to stop by step do
res &= i
if length(res)>9 then exit end if
end for
res = sprint(res)
catch e
res = e[E_USER]
end try
else
integer i = start
while (step>=0 and i<=stop)
or (step<=0 and i>=stop) do
res &= i
if length(res)>9 then exit end if
-- if i=stop then exit end if
-- if step=0 then exit end if
i += step
end while
res = sprint(res)
end if
printf(1,"%-43s: %s\n",{legend,res})
end procedure
 
for i=1 to 2 do
 ?iff(i=1?"for":"while")
test(-2, 2, 1, "Normal" ,i=1)
test(-2, 2, 0, "Zero increment" ,i=1)
test(-2, 2,-1, "Increments away from stop value" ,i=1)
test(-2, 2,10, "First increment is beyond stop value" ,i=1)
test( 2,-2, 1, "Start more than stop: positive increment" ,i=1)
test( 2, 2, 1, "Start equal stop: positive increment" ,i=1)
test( 2, 2,-1, "Start equal stop: negative increment" ,i=1)
test( 2, 2, 0, "Start equal stop: zero increment" ,i=1)
test( 0, 0, 0, "Start equal stop equal zero: zero increment",i=1)
puts(1,"\n")
end for
Output:
"for"
Normal                                     : {-2,-1,0,1,2}
Zero increment                             : for loop error, step is 0
Increments away from stop value            : {}
First increment is beyond stop value       : {-2}
Start more than stop: positive increment   : {}
Start equal stop: positive increment       : {2}
Start equal stop: negative increment       : {2}
Start equal stop: zero increment           : for loop error, step is 0
Start equal stop equal zero: zero increment: for loop error, step is 0

"while"
Normal                                     : {-2,-1,0,1,2}
Zero increment                             : {-2,-2,-2,-2,-2,-2,-2,-2,-2,-2}
Increments away from stop value            : {}
First increment is beyond stop value       : {-2}
Start more than stop: positive increment   : {}
Start equal stop: positive increment       : {2}
Start equal stop: negative increment       : {2}
Start equal stop: zero increment           : {2,2,2,2,2,2,2,2,2,2}
Start equal stop equal zero: zero increment: {0,0,0,0,0,0,0,0,0,0}

PL/I[edit]

loops:procedure options (main);
declare i fixed binary;
 
put skip list ('-2 to 2 by 1:');
do i = -2 to 2 by 1;
put edit (i) (f(3));
end;
put skip list ('-2 to 2 by 0: infinite loop, prints -2');
 
put skip list ('-2 to 2 by -1: [no values printed]');
do i = -2 to 2 by -1;
put edit (i) (f(3));
end;
 
put skip list ('-2 to 2 by 10:');
do i = -2 to 2 by 1;
put edit (i) (f(3));
end;
 
put skip list (' 2 to 2 by 1:');
do i = 2 to 2 by 1;
put edit (i) (f(3));
end;
 
put skip list (' 2 to 2 by -1:');
do i = 2 to 2 by -1;
put edit (i) (f(3));
end;
 
put skip list (' 2 to 2 by 0: infinite loop, prints 2');
put skip list (' 0 to 0 by 0: infinite loop, prints 0');
 
end loops;

Output:

-2 to 2 by  1:  -2 -1  0  1  2
-2 to 2 by  0: infinite loop, prints -2 
-2 to 2 by -1: [no values printed] 
-2 to 2 by 10:  -2 -1  0  1  2
 2 to 2 by  1:   2
 2 to 2 by -1:   2
 2 to 2 by  0: infinite loop, prints 2 
 0 to 0 by  0: infinite loop, prints 0 

Python[edit]

Python has the range function.

import re
from itertools import islice # To limit execution if it would generate huge values
# list(islice('ABCDEFG', 2)) --> ['A', 'B']
# list(islice('ABCDEFG', 4)) --> ['A', 'B', 'C', 'D']
 
 
data = '''
start stop increment Comment
-2 2 1 Normal
-2 2 0 Zero increment
-2 2 -1 Increments away from stop value
-2 2 10 First increment is beyond stop value
2 -2 1 Start more than stop: positive increment
2 2 1 Start equal stop: positive increment
2 2 -1 Start equal stop: negative increment
2 2 0 Start equal stop: zero increment
0 0 0 Start equal stop equal zero: zero increment
'''

 
table = [re.split(r'\s\s+', line.strip()) for line in data.strip().split('\n')]
#%%
for _start, _stop, _increment, comment in table[1:]:
start, stop, increment = [int(x) for x in (_start, _stop, _increment)]
print(f'{comment.upper()}:\n range({start}, {stop}, {increment})')
values = None
try:
values = list(islice(range(start, stop, increment), 999))
except ValueError as e:
print('  !!ERROR!!', e)
if values is not None:
if len(values) < 22:
print(' =', values)
else:
print(' =', str(values[:22])[:-1], '...')
 
Output:
NORMAL:
  range(-2, 2, 1)
    = [-2, -1, 0, 1]
ZERO INCREMENT:
  range(-2, 2, 0)
  !!ERROR!! range() arg 3 must not be zero
INCREMENTS AWAY FROM STOP VALUE:
  range(-2, 2, -1)
    = []
FIRST INCREMENT IS BEYOND STOP VALUE:
  range(-2, 2, 10)
    = [-2]
START MORE THAN STOP: POSITIVE INCREMENT:
  range(2, -2, 1)
    = []
START EQUAL STOP: POSITIVE INCREMENT:
  range(2, 2, 1)
    = []
START EQUAL STOP: NEGATIVE INCREMENT:
  range(2, 2, -1)
    = []
START EQUAL STOP: ZERO INCREMENT:
  range(2, 2, 0)
  !!ERROR!! range() arg 3 must not be zero
START EQUAL STOP EQUAL ZERO: ZERO INCREMENT:
  range(0, 0, 0)
  !!ERROR!! range() arg 3 must not be zero

R[edit]

Aside from the second case, this behaviour is explained by two sentences of seq's documentation: "generates from, from+by, ..., up to the sequence value less than or equal to to. Specifying to - from and by of opposite signs is an error." As we can see, from is always included whenever an error is not thrown and to will be missed if it cannot be reached.

seq(from = -2, to = 2, by = 1)#Output: -2 -1  0  1  2
seq(from = -2, to = 2, by = 0)#Fails: "invalid '(to - from)/by'"
seq(from = -2, to = 2, by = -1)#Fails: As in the notes above - "Specifying to - from and by of opposite signs is an error."
seq(from = -2, to = 2, by = 10)#Output: -2
seq(from = 2, to = -2, by = 1)#Fails: Same as the third case.
seq(from = 2, to = 2, by = 1)#Output: 2
seq(from = 2, to = 2, by = -1)#Output: 2
seq(from = 2, to = 2, by = 0)#Output: 2
seq(from = 0, to = 0, by = 0)#Output: 0

Racket[edit]

#lang racket
 
(require racket/sandbox)
 
(define tests '([-2 2 1 "Normal"]
[-2 2 0 "Zero increment"]
[-2 2 -1 "Increments away from stop value"]
[-2 2 10 "First increment is beyond stop value"]
[2 -2 1 "Start more than stop: positive increment"]
[2 2 1 "Start equal stop: positive increment"]
[2 2 -1 "Start equal stop: negative increment"]
[2 2 0 "Start equal stop: zero increment"]
[0 0 0 "Start equal stop equal zero: zero increment"]))
 
(for ([test (in-list tests)])
(match-define (list st ed inc desc) test)
(printf "~a:\n (in-range ~a ~a ~a) = ~a\n\n"
desc st ed inc
(with-handlers ([exn:fail:resource? (thunk* 'timeout)])
(with-limits 1 #f
(sequence->list (in-range st ed inc))))))
Output:
Normal:
  (in-range -2 2 1) = (-2 -1 0 1)

Zero increment:
  (in-range -2 2 0) = timeout

Increments away from stop value:
  (in-range -2 2 -1) = ()

First increment is beyond stop value:
  (in-range -2 2 10) = (-2)

Start more than stop: positive increment:
  (in-range 2 -2 1) = ()

Start equal stop: positive increment:
  (in-range 2 2 1) = ()

Start equal stop: negative increment:
  (in-range 2 2 -1) = ()

Start equal stop: zero increment:
  (in-range 2 2 0) = ()

Start equal stop equal zero: zero increment:
  (in-range 0 0 0) = ()

Raku[edit]

(formerly Perl 6)

Works with: Rakudo version 2018.08

It would be odd to call ANY of these sequences "wrong" in Raku. Raku specifically has built in capability of working with infinite sequences. Just because a sequence is infinite, doesn't mean you can't define it, work with it or use values from it. Sure, if you try to reify the whole thing you may be waiting a while, but there is nothing preventing you from using a portion of it.

Raku sequence definitions specifically allow "ending points" that may never occur in the sequence. Since that is the case, you don't even really need to specify a stop value. You can just say stop at "whatever". Whatever is spelled "*" in Raku.

There is additional syntax you can add to stop at the nearest value, last value previous or first value successor to the "stop value" (Note I didn't say less than or greater than the stop value since the sequence can be ascending, descending or non-monotonic).

Also note: The iterator function for the sequence is literally a function. It is any expression that produces a value. These sequences all use simple arithmatic increments but that is not a limitation of the sequence operator.

# Given sequence definitions
# start stop inc. Comment
for -2, 2, 1, # Normal
-2, 2, 0, # Zero increment
-2, 2, -1, # Increments away from stop value
-2, 2, 10, # First increment is beyond stop value
2, -2, 1, # Start more than stop: positive increment
2, 2, 1, # Start equal stop: positive increment
2, 2, -1, # Start equal stop: negative increment
2, 2, 0, # Start equal stop: zero increment
0, 0, 0, # Start equal stop equal zero: zero increment
 
# Additional "problematic" sequences
1, Inf, 3, # Endpoint literally at infinity
0, π, τ/8, # Floating point numbers
1.4, *, -7.1 # Whatever
 
-> $start, $stop, $inc {
my $seq = flat ($start, *+$inc$stop);
printf "Start: %3s, Stop: %3s, Increment: %3s | ", $start, $stop.Str, $inc;
# only show up to the first 15 elements of possibly infinite sequences
put $seq[^15].grep: +*.defined
}
 
# For that matter the start and end values don't need to be numeric either. Both
# or either can be a function, list, or other object. Really anything that a
# "successor" function can be defined for and produces a value.
say "\nDemonstration of some other specialized sequence operator functionality:";
# Start with a list, iterate by multiplying the previous 3 terms together
# and end with a term defined by a function.
put 1, -.5, 2.sqrt, * × * × **.abs < 1e-2;
 
# Start with an array, iterate by rotating, end when 0 is in the last place.
say [0,1,2,3,4,5], *.rotate(-1).Array!*.tail;
 
# Iterate strings backwards.
put 'xp''xf';
Output:
Start:  -2, Stop:   2, Increment:   1 | -2 -1 0 1 2
Start:  -2, Stop:   2, Increment:   0 | -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2
Start:  -2, Stop:   2, Increment:  -1 | -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16
Start:  -2, Stop:   2, Increment:  10 | -2 8 18 28 38 48 58 68 78 88 98 108 118 128 138
Start:   2, Stop:  -2, Increment:   1 | 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Start:   2, Stop:   2, Increment:   1 | 2
Start:   2, Stop:   2, Increment:  -1 | 2
Start:   2, Stop:   2, Increment:   0 | 2
Start:   0, Stop:   0, Increment:   0 | 0
Start:   1, Stop: Inf, Increment:   3 | 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43
Start:   0, Stop: 3.141592653589793, Increment: 0.7853981633974483 | 0 0.7853981633974483 1.5707963267948966 2.356194490192345 3.141592653589793
Start: 1.4, Stop:   *, Increment: -7.1 | 1.4 -5.7 -12.8 -19.9 -27 -34.1 -41.2 -48.3 -55.4 -62.5 -69.6 -76.7 -83.8 -90.9 -98

Demonstration of some other specialized sequence operator functionality:
1 -0.5 1.4142135623730951 -0.7071067811865476 0.5000000000000001 -0.5000000000000002 0.176776695296637 -0.04419417382415928 0.0039062500000000095
([0 1 2 3 4 5] [5 0 1 2 3 4] [4 5 0 1 2 3] [3 4 5 0 1 2] [2 3 4 5 0 1] [1 2 3 4 5 0])
xp xo xn xm xl xk xj xi xh xg xf

REXX[edit]

Note that a do loop with zero by value, or a do loop that goes in the "wrong" direction is not considered an error in REXX as there are other methods of limiting the range (or stopping condition) within the loop body.   A special check was made in this REXX version to check for a runaway (race) condition.

The REXX language will cause the do loop index to be checked at the "head" of the do loop to see if the index falls within the specified iteration range   (if there is one).

/*REXX program demonstrates several versions of  DO  loops with  "unusual"  iterations. */
@.=; @.1= ' -2 2 1 ' /*"normal". */
@.2= ' -2 2 0 ' /*"normal", zero increment.*/
@.3= ' -2 2 -1 ' /*increases away from stop, neg increment.*/
@.4= ' -2 2 10 ' /*1st increment > stop, positive increment.*/
@.5= ' 2 -2 1 ' /*start > stop, positive increment.*/
@.6= ' 2 2 1 ' /*start equals stop, positive increment.*/
@.7= ' 2 2 -1 ' /*start equals stop, negative increment.*/
@.8= ' 2 2 0 ' /*start equals stop, zero increment.*/
@.9= ' 0 0 0 ' /*start equals stop, zero increment.*/
zLim= 10 /*a limit to check for runaway (race) loop.*/
/*a zero increment is not an error in REXX.*/
do k=1 while @.k\=='' /*perform a DO loop with several ranges. */
parse var @.k x y z . /*obtain the three values for a DO loop. */
say
say center('start of performing DO loop number ' k " with range: " x y z, 79, '═')
zz= 0
do j=x to y by z until zz>=zLim /* ◄─── perform the DO loop.*/
say ' j ───►' right(j, max(3, length(j) ) ) /*right justify J for alignment*/
if z==0 then zz= zz + 1 /*if zero inc, count happenings*/
end /*j*/
 
if zz>=zLim then say 'the DO loop for the ' k " entry was terminated (runaway)."
say center(' end of performing DO loop number ' k " with range: " x y z, 79, '─')
say
end /*k*/ /*stick a fork in it, we're all done. */
output:
══════════start of performing DO loop number  1  with range:  -2 2 1═══════════
   j ───►  -2
   j ───►  -1
   j ───►   0
   j ───►   1
   j ───►   2
────────── end  of performing DO loop number  1  with range:  -2 2 1───────────


══════════start of performing DO loop number  2  with range:  -2 2 0═══════════
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
   j ───►  -2
the DO loop for the  2  entry was terminated (runaway).
────────── end  of performing DO loop number  2  with range:  -2 2 0───────────


══════════start of performing DO loop number  3  with range:  -2 2 -1══════════
────────── end  of performing DO loop number  3  with range:  -2 2 -1──────────


══════════start of performing DO loop number  4  with range:  -2 2 10══════════
   j ───►  -2
────────── end  of performing DO loop number  4  with range:  -2 2 10──────────


══════════start of performing DO loop number  5  with range:  2 -2 1═══════════
────────── end  of performing DO loop number  5  with range:  2 -2 1───────────


═══════════start of performing DO loop number  6  with range:  2 2 1═══════════
   j ───►   2
─────────── end  of performing DO loop number  6  with range:  2 2 1───────────


══════════start of performing DO loop number  7  with range:  2 2 -1═══════════
   j ───►   2
────────── end  of performing DO loop number  7  with range:  2 2 -1───────────


═══════════start of performing DO loop number  8  with range:  2 2 0═══════════
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
   j ───►   2
the DO loop for the  8  entry was terminated (runaway).
─────────── end  of performing DO loop number  8  with range:  2 2 0───────────


═══════════start of performing DO loop number  9  with range:  0 0 0═══════════
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
   j ───►   0
the DO loop for the  9  entry was terminated (runaway).
─────────── end  of performing DO loop number  9  with range:  0 0 0───────────

Ruby[edit]

A Range with a step (without a block) results in an ArthmeticSequence (an object). A step size of zero is perfectly valid. To illustrate, a representation of the ArithmicSequence and it's size are shown.

examples = [
[ -2, 2, 1],
[ -2, 2, 0],
[ -2, 2, -1],
[ -2, 2, 10],
[ 2, -2, 1],
[ 2, 2, 1],
[ 2, 2, -1],
[ 2, 2, 0],
[ 0, 0, 0]
]
 
examples.each do |start, stop, step|
as = (start..stop).step(step)
puts "#{as.inspect} size: #{as.size}"
end
 
Output:
((-2..2).step(1)) size: 5

((-2..2).step(0)) size: Infinity ((-2..2).step(-1)) size: 0 ((-2..2).step(10)) size: 1 ((2..-2).step(1)) size: 0 ((2..2).step(1)) size: 1 ((2..2).step(-1)) size: 1 ((2..2).step(0)) size: Infinity ((0..0).step(0)) size: Infinity

Seed7[edit]

$ include "seed7_05.s7i";
 
const proc: testLoop (in integer: start, in integer: stop, in integer: incr, in string: comment) is func
local
const integer: limit is 10;
var integer: number is 0;
var integer: count is 0;
begin
writeln(comment);
write("Range(" <& start <& ", " <& stop <& ", " <& incr <& ") -> [ ");
block
for number range start to stop step incr do
write(number <& " ");
incr(count);
if count >= limit then
raise RANGE_ERROR;
end if;
end for;
exception
catch RANGE_ERROR: noop;
end block;
writeln("]");
writeln;
end func;
 
const proc: main is func
begin
testLoop(-2, 2, 1, "Normal");
testLoop(-2, 2, 0, "Zero increment");
testLoop(-2, 2, -1, "Increments away from stop value");
testLoop(-2, 2, 10, "First increment is beyond stop value");
testLoop( 2, -2, 1, "Start more than stop: positive increment");
testLoop( 2, 2, 1, "Start equal stop: positive increment");
testLoop( 2, 2, -1, "Start equal stop: negative increment");
testLoop( 2, 2, 0, "Start equal stop: zero increment");
testLoop( 0, 0, 0, "Start equal stop equal zero: zero increment");
end func;
Output:
Normal
Range(-2, 2, 1) -> [ -2 -1 0 1 2 ]

Zero increment
Range(-2, 2, 0) -> [ -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 ]

Increments away from stop value
Range(-2, 2, -1) -> [ -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 ]

First increment is beyond stop value
Range(-2, 2, 10) -> [ -2 ]

Start more than stop: positive increment
Range(2, -2, 1) -> [ ]

Start equal stop: positive increment
Range(2, 2, 1) -> [ 2 ]

Start equal stop: negative increment
Range(2, 2, -1) -> [ 2 1 0 -1 -2 -3 -4 -5 -6 -7 ]

Start equal stop: zero increment
Range(2, 2, 0) -> [ 2 2 2 2 2 2 2 2 2 2 ]

Start equal stop equal zero: zero increment
Range(0, 0, 0) -> [ 0 0 0 0 0 0 0 0 0 0 ]

Vala[edit]

Translation of: C#
static void example(int start, int stop, int increment, string comment) {
const int MAX_ITER = 9;
int iteration = 0;
stdout.printf("%-50s", comment);
for (int i = start; i <= stop; i += increment) {
stdout.printf("%3d ", i);
if (++iteration > MAX_ITER) break;
}
stdout.printf("\n");
}
 
void main () {
example(-2, 2, 1, "Normal");
example(-2, 2, 0, "Zero increment");
example(-2, 2, -1, "Increments away from stop value");
example(-2, 2, 10, "First increment is beyond stop value");
example(2, -2, 1, "Start more than stop: positive increment");
example(2, 2, 1, "Start equals stop: positive increment");
example(2, 2, -1, "Start equals stop: negative increment");
example(2, 2, 0, "Start equals stop: zero increment");
example(0, 0, 0, "Start equals stop equal zero: zero increment");
}
Output:
Normal                                             -2  -1   0   1   2 
Zero increment                                     -2  -2  -2  -2  -2  -2  -2  -2  -2  -2 
Increments away from stop value                    -2  -3  -4  -5  -6  -7  -8  -9 -10 -11 
First increment is beyond stop value               -2 
Start more than stop: positive increment          
Start equals stop: positive increment               2 
Start equals stop: negative increment               2   1   0  -1  -2  -3  -4  -5  -6  -7 
Start equals stop: zero increment                   2   2   2   2   2   2   2   2   2   2 
Start equals stop equal zero: zero increment        0   0   0   0   0   0   0   0   0   0 

VBA[edit]

Public Sub LoopsWrongRanges()
Call Example(-2, 2, 1, "Normal")
Call Example(-2, 2, 0, "Zero increment")
Call Example(-2, 2, -1, "Increments away from stop value")
Call Example(-2, 2, 10, "First increment is beyond stop value")
Call Example(2, -2, 1, "Start more than stop: positive increment")
Call Example(2, 2, 1, "Start equal stop: positive increment")
Call Example(2, 2, -1, "Start equal stop: negative increment")
Call Example(2, 2, 0, "Start equal stop: zero increment")
Call Example(0, 0, 0, "Start equal stop equal zero: zero increment")
End Sub
Private Sub Example(start As Integer, stop_ As Integer, by As Integer, comment As String)
Dim i As Integer
Dim c As Integer
Const limit = 10
c = 0
Debug.Print start; " "; stop_; " "; by; " | ";
For i = start To stop_ Step by
Debug.Print i & ",";
c = c + 1
If c > limit Then Exit For
Next i
Debug.Print
Debug.Print comment & vbCrLf
End Sub
 
Output:
-2   2   1  | -2,-1,0,1,2,

Normal

-2 2 0 | -2,-2,-2,-2,-2,-2,-2,-2,-2,-2,-2, Zero increment

-2 2 -1 | Increments away from stop value

-2 2 10 | -2, First increment is beyond stop value

2 -2 1 | Start more than stop: positive increment

2 2 1 | 2, Start equal stop: positive increment

2 2 -1 | 2, Start equal stop: negative increment

2 2 0 | 2,2,2,2,2,2,2,2,2,2,2, Start equal stop: zero increment

0 0 0 | 0,0,0,0,0,0,0,0,0,0,0,

Start equal stop equal zero: zero increment

Visual Basic .NET[edit]

Compiler: >= Visual Studio 2012

VB.NET's For loop accepts a starting and ending value and optional step.

Since the task mentions generators and a range of values, this implementation places the for loop in an iterator function (called a generator in many other languages) and yields the iteration variable in every iteration. The resulting IEnumerable object (whose actual class is generated by the compiler) is lazily-evaluated (i.e., it is run only when a new value is requested, and only until the next Yield statement).

The number of iterations is limited to 10 by the test code.

Module Program
Sub Main()
Example(-2, 2, 1, "Normal")
Example(-2, 2, 0, "Zero increment")
Example(-2, 2, -1, "Increments away from stop value")
Example(-2, 2, 10, "First increment is beyond stop value")
Example(2, -2, 1, "Start more than stop: positive increment")
Example(2, 2, 1, "Start equal stop: positive increment")
Example(2, 2, -1, "Start equal stop: negative increment")
Example(2, 2, 0, "Start equal stop: zero increment")
Example(0, 0, 0, "Start equal stop equal zero: zero increment")
End Sub
 
' Stop is a keyword and must be escaped using brackets.
Iterator Function Range(start As Integer, [stop] As Integer, increment As Integer) As IEnumerable(Of Integer)
For i = start To [stop] Step increment
Yield i
Next
End Function
 
Sub Example(start As Integer, [stop] As Integer, increment As Integer, comment As String)
' Add a space, pad to length 50 with hyphens, and add another space.
Console.Write((comment & " ").PadRight(50, "-"c) & " ")
 
Const MAX_ITER = 9
 
Dim iteration = 0
' The For Each loop enumerates the IEnumerable.
For Each i In Range(start, [stop], increment)
Console.Write("{0,2} ", i)
 
iteration += 1
If iteration > MAX_ITER Then Exit For
Next
 
Console.WriteLine()
End Sub
End Module
Output:
Normal ------------------------------------------- -2 -1  0  1  2
Zero increment ----------------------------------- -2 -2 -2 -2 -2 -2 -2 -2 -2 -2
Increments away from stop value ------------------
First increment is beyond stop value ------------- -2
Start more than stop: positive increment ---------
Start equal stop: positive increment -------------  2
Start equal stop: negative increment -------------  2
Start equal stop: zero increment -----------------  2  2  2  2  2  2  2  2  2  2
Start equal stop equal zero: zero increment ------  0  0  0  0  0  0  0  0  0  0

Wren[edit]

Library: Wren-fmt
import "/fmt" for Fmt
 
var loop = Fn.new { |start, stop, inc|
System.write("%(Fmt.v("dm", 3, [start, stop, inc], 0, " ", "[]")) -> ")
var count = 0
var limit = 10
var i = start
while (i <= stop) {
System.write("%(i) ")
count = count + 1
if (count == limit) break
i = i + inc
}
System.print()
}
 
var tests = [
[-2, 2, 1], [-2, 2, 0], [-2, 2, -1], [-2, 2, 10], [2, -2, 1], [2, 2, 1], [2, 2, -1], [2, 2, 0], [0, 0, 0]
]
for (test in tests) loop.call(test[0], test[1], test[2])
Output:
[ -2   2   1] -> -2 -1 0 1 2 
[ -2   2   0] -> -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 
[ -2   2  -1] -> -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 
[ -2   2  10] -> -2 
[  2  -2   1] -> 
[  2   2   1] -> 2 
[  2   2  -1] -> 2 1 0 -1 -2 -3 -4 -5 -6 -7 
[  2   2   0] -> 2 2 2 2 2 2 2 2 2 2 
[  0   0   0] -> 0 0 0 0 0 0 0 0 0 0 


Yabasic[edit]

Translation of: FreeBASIC
data -2,2,1,"Normal",-2,2,0,"Zero increment",-2,2,-1,"Increments away from stop value"
data -2,2,10,"First increment is beyond stop value",2,-2,1,"Start more than stop: positive increment"
data 2,2,1,"Start equal stop: positive increment",2,2,-1,"Start equal stop: negative increment"
data 2,2,0,"Start equal stop: zero increment",0,0,0,"Start equal stop equal zero: zero increment"
 
for i = 1 to 9
contar = 0
read start, fin, inc, cmt$
print cmt$
print " Bucle de ", start, " a ", fin, " en incrementos de ", inc
for vr = start to fin step inc
print " Indice del bucle = ", vr
contar = contar + 1
if contar = 10 then
print " Saliendo de un bucle infinito"
break
endif
next vr
print " Bucle terminado\n\n"
next i
end
Output:
Normal
  Bucle de -2 a 2 en incrementos de 1
        Indice del bucle = -2
        Indice del bucle = -1
        Indice del bucle = 0
        Indice del bucle = 1
        Indice del bucle = 2
  Bucle terminado


Zero increment
  Bucle de -2 a 2 en incrementos de 0
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Indice del bucle = -2
        Saliendo de un bucle infinito
  Bucle terminado


Increments away from stop value
  Bucle de -2 a 2 en incrementos de -1
  Bucle terminado


First increment is beyond stop value
  Bucle de -2 a 2 en incrementos de 10
        Indice del bucle = -2
  Bucle terminado


Start more than stop: positive increment
  Bucle de 2 a -2 en incrementos de 1
  Bucle terminado


Start equal stop: positive increment
  Bucle de 2 a 2 en incrementos de 1
        Indice del bucle = 2
  Bucle terminado


Start equal stop: negative increment
  Bucle de 2 a 2 en incrementos de -1
        Indice del bucle = 2
  Bucle terminado


Start equal stop: zero increment
  Bucle de 2 a 2 en incrementos de 0
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Indice del bucle = 2
        Saliendo de un bucle infinito
  Bucle terminado


Start equal stop equal zero: zero increment
  Bucle de 0 a 0 en incrementos de 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Indice del bucle = 0
        Saliendo de un bucle infinito
  Bucle terminado


zkl[edit]

// zero increment (ie infnite loop) throws an error
// if stop is "*", the loop is has no end (ie infinite)
// stop is included unless step steps skips it
// if start > stop is a dead loop
// ranges ([a..b,c]) are lazy lists
fcn looper([(start,stop,increment)]){
print(" %3s  %3s\t%2d --> ".fmt(start,stop,increment));
try{ foreach n in ([start..stop,increment]){ print(n," ") } }
catch{ print(__exception) }
println();
}
println("start stop increment");
T( T(-2,2,1),T(-2,2,0),T(-2,2,-1),T(-2,2,10),T( 2,-2,1),
T( 2,2,1),T( 2,2,-1),T( 2,2,0),T( 0,0,0),
T(0.0, (0.0).pi, 0.7853981633974483), T("a","e",1), T("e","a",1) )
.apply2(looper); // apply2 is apply (map) without saving results
Output:
start stop  increment
  -2    2	 1 --> -2 -1 0 1 2 
  -2    2	 0 --> ValueError(range: step == 0)
  -2    2	-1 --> 
  -2    2	10 --> -2 
   2   -2	 1 --> 
   2    2	 1 --> 2 
   2    2	-1 --> 2 
   2    2	 0 --> ValueError(range: step == 0)
   0    0	 0 --> ValueError(range: step == 0)
   0  3.14159	 0 --> 0 0.785398 1.5708 2.35619 3.14159 
   a    e	 1 --> a b c d e 
   e    a	 1 -->