Szathmáry László honlapja @ DEIK | DLang / Prettify a number

(1) prettify a number
def main(): n = 123456 print(n) # 123456 print(f"{n:,}") # 123,456	import std.stdio; import std.format; void main() { int n = 123456; writeln(n); // 123456 writefln("%,s", n); // 123,456 string s = format("%,s", n); writeln(s); // 123,456 }

If you have a huge number as a string (for instance, you converted a BigInt to string), then you can use this manual method:

(2) manual solution

#!/usr/bin/env rdmd

import std.stdio;
import std.algorithm;

string pretty_number(const string s) pure
{
char[] result;

auto i = 0;
foreach_reverse (c; s)
{
if (i % 3 == 0 && i > 0)
{
result ~= ",";
}
result ~= c;
++i;
}
result.reverse();

return result.idup;
}

void main()
{
writeln(pretty_number("123456789")); // 123,456,789
}