Thanks for your answer but:
import std.stdio;
import std.conv;
void main()
{
write("Insert number: ");
string s = readln();
auto i = to!int(s);
}compiles but after i enter a number and press the enter key i get: std.conv.ConvException@.\..\..\src\phobos\std\conv.d(1595): Can't convert value ` ' of type string to type int ---------------- 41DECC 41DD43 4027F3 402475 402D6C 402DB0 4029A7 4BBA79 ---------------- what's wrong?
