CODEWITHSUNDEEP
c#regex
Merdigon
Merdigon

Reputation: 5

C# Regex - endless matching

I wanted to use Regex to get data from repeated XML tag:

<A>cat</A><A>dog</A>

So I've created Regex: 

<A>(.*?)</A>

and code:

string text = "<A>asdasd</A><A>dsfsd</A>";
string regex = @"<A>(.*?)</A>";

Regex rgx = new Regex(regex);
Match match = rgx.Match(text);
while(match.Success)
{
     i++;
     Console.WriteLine(match.Groups[1].Value);
     match.NextMatch();
}

But when I start my code, my loop is endless and never stop.

Can someone help me find what's wrong with code? Or find another solution? (I don't want to deserialize XML).

Upvotes: 0

Views: 323

Answers (3)

Innat3
Innat3

Reputation: 3576

Just use Regex.Matches to load them all into a collection, and proceed to iterate it.

string text = "<A>asdasd</A><A>dsfsd</A>";
string regex = @"<A>(.*?)</A>";

foreach (Match m in Regex.Matches(text, regex))
{
    Console.WriteLine(m.Groups[1].Value);
}

Or single line using Linq:

Regex.Matches(text, regex).Cast<Match>().ToList().ForEach(m => Console.WriteLine(m.Groups[1].Value));

Upvotes: 1

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626747

While the failure reason is that you did not assign the next match to match, you can actually use Regex.Matches to get all the substrings you need in one go without the need for an explicit loop:

var results = rgx.Matches(text)
                .Cast<Match>()
                .Select(m => m.Groups[1].Value);
Console.WriteLine(string.Join("\n", results));

See the C# online demo:

var text = "<A>asdasd</A><A>dsfsd</A>";
var regex = @"<A>(.*?)</A>";
var rgx = new Regex(regex);
var results = rgx.Matches(text)
           .Cast<Match>()
           .Select(m => m.Groups[1].Value);
Console.WriteLine(string.Join("\n", results));  
// asdasd
// dsfsd

Upvotes: 1

James Thorpe
James Thorpe

Reputation: 32202

This:

match.NextMatch();

just returns the next match, it doesn't change the state of match itself. You need to update the variable:

match = match.NextMatch();

Upvotes: 7

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