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

[ag0aep6g via Digitalmars-d-learn]

On Friday, 4 March 2022 at 19:51:44 UTC, matheus wrote:
import std.datetime.stopwatch;
import std.stdio: write, writeln, writef, writefln;
import std;
void printStrTim(string s,StopWatch sw){
    writeln("\nstr: ", s
            ,"\nTim(ms): ", sw.peek.total!"msecs"
            ,"\nTim(us): ", sw.peek.total!"usecs"
           );
}

void main(){
    auto sw = StopWatch(AutoStart.no);
    string s, str = "4A0B1de!2C9~6";
    int j;

    sw.start();
    for(j=0;j<1_000_000;++j){
        s="";
        foreach(i;str){
            (i >= '0' && i <= '9') ? s~=i : null;
        }
    }
    sw.stop();
    printStrTim(s,sw);

    s = "";
    sw.reset();
    sw.start();
    for(j=0;j<1_000_000;++j){
        s="";
        s = str.filter!(ch => ch.isDigit).to!string;
    }
    sw.stop();
    printStrTim(s,sw);
}

Prints:

str: 401296
Tim(ms): 306
Tim(us): 306653

str: 401296
Tim(ms): 1112
Tim(us): 1112648

-------------------------------

Unless I did something wrong (If anything please tell).

The second version involves auto-decoding, which isn't actually 
needed. You can work around it with `str.byCodeUnit.filter!...`. 
On my machine, times become the same then.

Typical output:

str: 401296
Tim(ms): 138
Tim(us): 138505

str: 401296
Tim(ms): 137
Tim(us): 137376