Digit grouping

[ghost]

Nim seems to have no way to format a number with commas or digit grouping. Other languages offer this, for example C:

#define _XOPEN_SOURCE 700
#include <locale.h>
#include <stdio.h>
int main() {
   setlocale(LC_ALL, "");
   printf("%'d\n", 1000);
}

Python:

f'{1000:,}'

JavaScript:

(1000).toLocaleString();

PHP:

number_format(1000);

Go:

package main
import "golang.org/x/text/language"
import "golang.org/x/text/message"
func main() {
   message.NewPrinter(language.English).Println(1000)
}

D:

import std.format, std.stdio;
void main() {
   auto aa = "%,d".format(1000);
   writeln(aa);
}

(EDIT) links

• https://docs.python.org/3/library/string.html#formatspec
• https://www.python.org/dev/peps/pep-0378/

[narimiran]

Nim seems to have no way to format a number with commas or digit grouping.

strutils.insertSep

[mratsim]

Probably an option to add to strformat formatting of numbers

[Araq]

Well yes, but since it's deterministic, .replace('.', ',') will always work well.

[qqtop]

import nimcx
let a = 1234567890
let b = -10007887236.4567
echo ff2(a,2)
echo ff2(b,5)

gives

1,234,567,890.00
-10,007,887,236.45670

[ghost]

@qqtop thanks, but looks like that doesnt work on windows

[qqtop]

nimcx is made for linux only but you are free to just extract the relevant procs and adapt / improve them for windows . The procs sit in cxglobal.nim

[krux02]

just a small remark: (1000.5).toLocaleString(); returns '1.000,5' on my system. I don't know if you ever want that.

[ghost]

@narimiran I just noticed an issue:

import strutils
const aa = $(1234.56)
echo aa.insertSep(',')

Result:

1,234,.56

[narimiran]

It is not an issue, it works as advertised: the algorithm works with any string s, meaning it treats 123456, 123.45, abcdef, !@#$%^, etc. completely the same — it inserts a separator after n characters from the right.

[krux02]

@cup can we mark this feauter request then as resolved?

[ghost]

@krux02 um, no? It would be resolved if it was in the standard library, or if the developers are currently officially refusing to do that.

[timotheecour]

for the reverse direction, see https://github.com/nim-lang/Nim/pull/15421#issuecomment-746863623

[ringabout]

See also https://www.python.org/dev/peps/pep-0378 https://www.python.org/dev/peps/pep-0515

[timotheecour]

https://www.python.org/dev/peps/pep-0515/ is already in nim, so i guess it's mostly https://www.python.org/dev/peps/pep-0378/ to consider

[ringabout]

yeah, pep515 also introduces _ option for f-string. Before f-string only support , option.

[ringabout]

using sprintf make it a bit hard to extend.

needs https://github.com/nim-lang/Nim/issues/13365 to move on.