Finding numbers in a string using C# / Regex

Question

I need to have the ability to parse out a series of numbers in a string in C# / Regex. The numbers can be one or more digits long and are always at the end of the string and after the word "ID" for example:

"Test 123 Test - ID 589"

In this case I need to be able to pick out 589.

Any suggestions? Some of the code That I have used picks out all the numbers which is not what I want to do.

Thanks

Searching yields [this](http://stackoverflow.com/questions/6616969/finding-all-numbers-in-a-string) — afuzzyllama, Aug 25 '11 at 15:31
if you know that the number you want to pick is always going to be at the end of the string, i will not suggest you to use Regular Expressions here. — Asdfg, Aug 25 '11 at 15:48

score 3 · Answer 1 · answered Aug 25 '11 at 15:27

3

I would use the pattern @"ID (\d+)$"

using System.Text.RegularExpressions;
var s = "Test 123 Test - ID 589";
var match = Regex.Match(s, @"ID (\d+)$");
int? id = null;
if (match.Success) {
  id = int.Parse(match.Groups[1].Value);    
}

answered Aug 25 '11 at 15:27

James Kyburz

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score 1 · Accepted Answer · answered Aug 25 '11 at 15:45

1

string resultString = null;
try {
    Regex regexObj = new Regex(@"ID (?<digit>\d+)$");
    resultString = regexObj.Match(subjectString).Groups["digit"].Value;
} catch (ArgumentException ex) {
// Syntax error in the regular expression
}

answered Aug 25 '11 at 15:45

Dariusz

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score 1 · Answer 3 · answered Aug 25 '11 at 15:51

1

foo.Substring(foo.IndexOf("ID")+3)

answered Aug 25 '11 at 15:51

Asdfg

11,362
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score 0 · Answer 4 · answered Aug 25 '11 at 15:35

This is the most specific pattern, in case not every line ends with a number you're interested in:

@"\bID\s+(\d+)$"

Note: Target numbers will be in capture group 1.

However, based on your description, you could just use this:

@"\d+$"

It simply looks for a string of numeric digits at the very end of each line. This is what I'd go with.

Finding numbers in a string using C# / Regex

4 Answers4