• Joel (13/13) Oct 14 2015 Is there a fast way to get a number out of a text input?
• Andrea Fontana (4/17) Oct 14 2015 What about "sdaz1.a3..44["?
• =?UTF-8?Q?Ali_=c3=87ehreli?= (32/45) Oct 14 2015 Regular expressions:
• Joel (2/2) Oct 14 2015 Thanks guys. I did think of regex, but I don't know how to learn

Joel <joelcnz gmail.com> writes:

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;
			}

Andrea Fontana <nospam example.com> writes:

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.

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 10/14/2015 12:14 AM, 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;
              }

Regular expressions:

import std.stdio;
import std.regex;

void main() {
     auto input = "sdaz1.5;[";
     auto pattern = ctRegex!(`([^-0-9.]*)([-0-9.]+)(.*)`);
     auto m = input.matchFirst(pattern);

     if (m)  {
         assert(m[0] == "sdaz1.5;[");    // whole
         assert(m[1] == "sdaz");         // before
         assert(m[2] == "1.5");          // number
         assert(m[3] == ";[");           // after
     }
}

1) I am not good with regular expressions. So, the floating point 
selector [-0-9.]+ is very primitive. I recommend that you search for a 
better one. :)

2) ctRegex is slow to compile. Replace ctRegex!(expr) with regex(expr) 
for faster compilations and slower execution (probably unnoticeably slow 
in most cases).

3) If you want to extract a number out of a constant string, 
formattedRead (or readf) can be used as well:

import std.stdio;
import std.format;

void main() {
     auto input = "Distance: 1.5 feet";
     double number;

     const quantity = formattedRead(input, "Distance: %f feet", &number);
     assert(number == 1.5);
}

Ali

Joel <joelcnz gmail.com> writes:

Thanks guys. I did think of regex, but I don't know how to learn 
it.