asked on 10/4/2011

Extract digit number from a string

Hello, just need an advice.

I have strings, each of them might contain digit number. For example,

string str1 = "abcdet5678sd"; // containg 5678
srting str2 = "dfg34567c"; // containing 2456

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I want to extract these numeric values.
Finally we will get

string new_str = "5678"
string new_str = "34567";

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The question is that we don't know how long of the digit number and what is the position.
Also it may not have a number in the string, in this case, just give a message.
Thanks for advice.

Regular Expressions C#

Last Comment

zhshqzyc

10/4/2011

Dirk Haest

10/4/2011

http://www.java2s.com/Code/CSharp/Language-Basics/Useregularexpressiontogetnumberfromstring.htm

using System;
using System.Data;
using System.Text.RegularExpressions;

class Class1{
        static void Main(string[] args){
      string IsNotNum = "111west";
      string IsNum = "  +111  ";
      string IsFloat = "  23.11  ";
      string IsExp = "  +23 e+11  ";
      
      Console.WriteLine(GetNumberFromStr(IsNum));    // +111
      Console.WriteLine(GetNumberFromStr(IsNotNum));  // 
      Console.WriteLine(GetNumberFromStr(IsFloat));  // 23.11
      Console.WriteLine(GetNumberFromStr(IsExp));    // 
        }
    public static string GetNumberFromStr(string str)
    {
      str = str.Trim();
      Match m = Regex.Match(str, @"^[\+\-]?\d*\.?[Ee]?[\+\-]?\d*$");
      return (m.Value);
    }
    
}

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zhshqzyc

10/4/2011

ASKER

Well, the code will get "+111" from "111west". But I only want to get "111".
And if the original string pattern likes "abc111west", I suspect whether it works or not?

Dirk Haest

10/4/2011

Try the following:
string str = "abc111west";
str = string.Join(null, System.Text.RegularExpressions.Regex.Split(str, "[^\\d]"));

ASKER CERTIFIED SOLUTION