Regex: Selecting Text within Templated Syntax

I am trying to obtain the value part of this syntax:

[name:value]

I got as far as:

\[name:(\w*)]

Which matches the entire thing. Does anyone know the changes I would need to mak开发者_开发知识库e to select only value? (Bearing in mind that syntax will also be surrounded by other text.

The Match.Result method is what you want. See API documentation and documentation on Regex substitution patterns.

Use Regex.Match(input, pattern).Result("$1") to get what you want.

To give a complete example, here is the unit test I used to confirm that this solution would work:

[Test]
public void TestRegexMatchResult() {
    var input = "Other text [name:value] and other text";
    var pattern = @"\[name:(\w+)\]";

    Assert.AreEqual("value", Regex.Match(input, pattern).Result("$1"));
}

The test passes.

You can also go through a string and extract multiple occurrences of the pattern:

[Test]
public void TestRegexMatchesResult() {
    var input = "Some [name:value] pairs [name:something] here.";
    var pattern = @"\[name:(\w+)\]";

    var results = Regex.Matches(input, pattern).OfType<Match>()
        .Select(match => match.Result("$1"));

    Assert.AreEqual(2, results.Count());

    Assert.AreEqual("value", results.ElementAt(0));
    Assert.AreEqual("something", results.ElementAt(1));
}

Finally, if you need to abstract this to something other than "name", you can do this:

[Test]
public void TestMatchingNameAndValue() {
    var input = "[key:value] [another_key:some_other_value]";
    var pattern = @"\[(\w+):(\w+)\]";

    var results = Regex.Matches(input, pattern).OfType<Match>()
        .Select(match => new KeyValuePair<string, string>(
            match.Result("$1"),
            match.Result("$2")));

    Assert.AreEqual(2, results.Count());

    Assert.AreEqual("key", results.ElementAt(0).Key);
    Assert.AreEqual("value", results.ElementAt(0).Value);
    Assert.AreEqual("another_key", results.ElementAt(1).Key);
    Assert.AreEqual("some_other_value", results.ElementAt(1).Value);
}

The regex will always match the entire string, but you can access the matching portion with the Groups member collection:

public static void Main()
{
   string pattern = @"(\d{3})-(\d{3}-\d{4})";
   string input = "212-555-6666 906-932-1111 415-222-3333 425-888-9999";
   MatchCollection matches = Regex.Matches(input, pattern);

   foreach (Match match in matches)
   {
      Console.WriteLine("Area Code:        {0}", match.Groups[1].Value);
      Console.WriteLine("Telephone number: {0}", match.Groups[2].Value);
      Console.WriteLine();
   }
   Console.WriteLine();
}

(this example is taken from the page referenced)

You could use lookaround to only match value.

Search for (?<=\[name:)\w+(?=])

This means: Match one or more alphanumeric characters, if and only if they are preceded by [name and followed by ]. Note that it's not necessary to escape the ].