C＃中的递归正则表达式

Question

I am practicing regex with C#. This is my code:

string test =
    "this is whole new line, with different parameters 10.1.2.1, 10.1.5.1, 10.1.3.1";
string a = Regex.Match(test, "10.[0-9].[0-9]+.[0-9]+").Value;
Console.WriteLine(a);

The result is 10.1.2.1 . It finds the first match and that's it.

How can I perform this function recursively ? Do I need to add some extra code or is there a regex class which has this as a built in function (which I would prefer)?

Answer 1

You are explicitly asking for only one match, using the Match method. You should use Matches instead, and iterate over the result:

string test = "this is whole new line, with different parameters 10.1.2.1, 10.1.5.1, 10.1.3.1";
foreach(Match result in Regex.Matches(test, "10.[0-9].[0-9]+.[0-9]+"))
{
    Console.WriteLine(result);  
}

That code will print the following:

10.1.2.1
10.1.5.1
10.1.3.1

Answer 2

From the documentation of RegEx.Match() :

Searches the specified input string for the first occurrence of the regular expression specified in the Regex constructor.

It does exactly what it should, returns the first match. If you want all matches you should use RegEx.Matches(string, string) .