How to remove all characters from a string, except the integers?

[BoQsc]

On Thursday, 3 March 2022 at 13:25:32 UTC, Stanislav Blinov wrote:
> On Thursday, 3 March 2022 at 12:14:13 UTC, BoQsc wrote:
>
>> I need to check if a string contains integers,
>> and if it contains integers, remove all the regular string 
>> characters.
>> I've looked around and it seems using regex is the only 
>> closest solution.
>
> ```d
> import std.stdio;
> import std.algorithm : find, filter;
> import std.conv : to;
> import std.uni : isNumber;
>
> void main(string[] args){
>     if (args.length > 1){
> 	
>         auto filtered = () {
>             auto r = args[1].find!isNumber; // check if a 
> string contains integers
>             return r.length ?
>                    r.filter!isNumber.to!string // and if it 
> does, keep only integers
>                    : args[1];                  // otherwise 
> keep original
>         } ();
>
>         filtered.writeln;
> 		
>     } else {
>         write("Please write an argument.");
>     }
> }
> ```

D language should be renamed into Exclamation-mark language.
It feels overused everywhere and without a better alternative.