Question

In PHP I can use a foreach loop such that I have access to both the key and value for example:

foreach($array as $key => $value)

I have the following code:

Regex regex = new Regex(pattern);
MatchCollection mc = regex.Matches(haystack);
for (int i = 0; i < mc.Count; i++)
{
     GroupCollection gc = mc[i].Groups;
     Dictionary<string, string> match = new Dictionary<string, string>();
     for (int j = 0; j < gc.Count; j++)
     {
        //here
     }
     this.matches.Add(i, match);
}

at //here I’d like to match.add(key, value) but I cannot figure out how to get the key from the GroupCollection, which in this case should be the name of the capturing group. I know that gc["goupName"].Value contains the value of the match.

Answer 1

In .NET, the group names are available against the Regex instance:

// outside all of the loops
string[] groupNames = regex.GetGroupNames();

Then you can iterate based on this:

Dictionary<string, string> match = new Dictionary<string, string>();
foreach(string groupName in groupNames) {
    match.Add(groupName, gc[groupName].Value);
}

Or if you want to use LINQ:

var match = groupNames.ToDictionary(
            groupName => groupName, groupName => gc[groupName].Value);