c# - How to check if string contains single occurence of substring?

Question

I have this:

string strings = "a b c d d e";

And I need something similar to string.Contains(), but I need to know not only whether a string is present(in case above a letter), but also if it is present only ONE SINGLE time.

How can I achieve this?

Answer 1

You can use LastIndexOf(String) and IndexOf(String) and verify that the values returned are equal. Of course also check if the String is found at all(i.e the returned value is not -1).