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

Updated extension method utilizing Span to minimize new string creation

    public static string ReplaceFirstOccurrence(this string source, string search, string replace) {
        int index = source.IndexOf(search);
        if (index < 0) return source;
        var sourceSpan = source.AsSpan();
        return string.Concat(sourceSpan.Slice(0, index), replace, sourceSpan.Slice(index + search.Length));
    }