I have many text rows, and I must find some rows, and to change them.
I wrote such regex rule:
^(Position) ([0-9]+)$ For example, I must find all such rows:
Position 10
Position 11
Position 12
Now I must increase numbers at 5. How can I do it through Regex? I try to wrote such regex rule:
$1 {$2+ 5} I need get result:
Position 15
Position 16
Position 17
But I have got:
Position {10 +5}
Position {11+5}
Position {12+5}
the Regex Replace function takes either a string, or a function. you used the string replacement, so just the string is inserted. if you want an integer operation, you need to use the replace with function method.
http://msdn.microsoft.com/library/cft8645c(v=vs.80).aspx
this code is not correct, it should just show the way how it could be done
Regex.Replace("^(Position) ([0-9]+)$", ReplaceFunction); public string ReplaceFunction(Match m) { return "Position " + (int.Parse(m.Groups[2].Value) + 5); }; 
var result = Regex.Replace(input, and then your other two parameters. And you need Groups[2] as Groups[0] is the whole match, not the first group.
string input = @"Position 10"; string output = Regex.Replace(input, "^Position ([0-9]+)$", match => "Position " + Int32.Parse(match.Groups[1].Value) + 5); 