Comparing strings and get the first place where they vary from eachother

Question

I want to get the first place where 2 string vary from each other. example: for these two strings: \"AAAB\" \"AAAAC\"

I want to get the result 4.

How do i d

Answer 1

You can create an extension method to do the trick:

public static class StringExtensions {
    public static int IndexOfDifferenceFrom(this string source, string compareTo)
    {
        for(var i = 0; i < source.Length && i < compareTo.Length; ++i) {
            if (source[i] != compareTo[i]) {
                return i;
            }
        }

        return source.Length < compareTo.Length ? source.Length : compareTo.Length;
    }

}

Or, for a LINQy solution:

var index = string1.Where((ch, i) => string2[i] == ch).Select((ch, i) => i).DefaultIfEmpty(-1).First();