How do I replace the *first instance* of a string in .NET?

Question

I want to replace the first occurrence in a given string.

How can I accomplish this in .NET?

Answer 1

C# extension method that will do this:

public static class StringExt
{
    public static string ReplaceFirstOccurrence(this string s, string oldValue, string newValue)
    {
         int i = s.IndexOf(oldValue);
         return s.Remove(i, oldValue.Length).Insert(i, newValue);    
    } 
}

Enjoy

Answer 2

This example abstracts away the substrings (but is slower), but is probably much fast than a RegEx:

var parts = contents.ToString().Split(new string[] { "needle" }, 2, StringSplitOptions.None);
return parts[0] + "replacement" + parts[1];