User input parsing

[Andrea Fontana via Digitalmars-d-learn]

On Wednesday, 14 October 2015 at 07:14:45 UTC, Joel wrote:
> Is there a fast way to get a number out of a text input?
>
> Like getting '1.5' out of 'sdaz1.5;['.
>
> Here's what I have at the moment:
> 			string processValue(string s) {
> 				string ns;
> 				foreach(c; s) {
> 					if (c >= '0' && c <= '9')
> 						ns ~= c;
> 					else if (c == '.')
> 						ns ~= '.';
> 				}
>
> 				return ns;
> 			}

What about "sdaz1.a3..44["?

Anyway, you could use an appender, or reserve memory to speed up 
your code.