C＃枚举正则表达式匹配项

Question

What is the best way to enumerate a regex-replacement in C#.

For example if I wanted every "<intent-filter" match to be replaced by "<intent-filter android:label=label#" . The # sign is a incremental digit. What would be the best way to code it?

Answer 1

You can use an incremented counter in the anonymous method specified as the MatchEvaluator callback. The (?<=…) is positive lookbehind; it is matched by the regex evaluator, but not removed.

string input = "a <intent-filter data=a /> <intent-filter data=b />";
int count = 0;
string result = Regex.Replace(input, @"(?<=\<intent-filter)", 
    _ => " android:label=label" + count++);

Answer 2

Don't bother with Regexes for this one. Do something along the lines of:

var pieces = text.Split(new string[] { "xx" });
var sb = new StringBuilder();
var idx = 0;
foreach (var piece in pieces)
{
    sb.Append(piece);
    sb.Append(" android:label=label");
    sb.Append(idx);
}
// oops, homework assignment: remove the last "<intent-filter android:label=label#"