I have a string
work 1 work 2 work 3 work 4 work 5
I want to obtain
work 1 work 21 work 321 work 4321 work 54321
I use this command but not work
(?<=work\s(\d)+.)(work)(\s\d+)
$2$3$1
The problem is that it does not record the information replaced after the first occurrence and could do to save the changes after each occurrence.
When I apply the command I get
work 1 work 21 work 32 work 43 work 54
You do not actually need an overlapping regex matching, you need to be able to match each work+space+digits and save the digits value to update at each iteration.
The regex is reduced to a mere work (?<num>\d+) (matches work, a space and captures one or more digits into the "num" group).
Use a callback method inside a Regex.Replace method:
using System;
using System.IO;
using System.Text.RegularExpressions;
using System.Linq;
public class Test
{
public static string num = string.Empty;
public static void Main()
{
var s = "work 1 work 2 work 3 work 4 work 5";
Console.WriteLine(Regex.Replace(s, @"work (?<num>\d+)", Repl));
}
public static string Repl(Match m)
{
num = m.Groups["num"].Value + num;
return string.Format("work {0}", num);
}
}
See the C# demo
You can try Regex.Replace while aggregating matches :
String source = "work 1 work 2 work 3 work 4 work 5";
String aggregate = "";
// work 1 work 21 work 321 work 4321 work 54321
String result = Regex.Replace(source, @"\d+", // or @"(?<=work\s)\d+" pattern
match => aggregate = match.Value + aggregate);
sln's and Wiktor Stribiżew's ones) exploit the same idea: regular expression + aggregation; the implementations, however, are slightly different (the answers uses groups, when I've performed look behind in @"(?<=work\s)\d+" pattern; I prefer lambda to delegates etc.). So the similar examples are the other answers\d+ regex matching one or zero digits will match any digit sequences, not only after "work ". @zero625: BTW, if an answer proved helpful, please always consider upvoting it.