How to replace part of string by position?

Question

I have this string: ABCDEFGHIJ

I need to replace from position 4 to position 5 with the string ZX

It will look like this: ABC

Answer 1

You could try something link this:

string str = "ABCDEFGHIJ";
str = str.Substring(0, 2) + "ZX" + str.Substring(5);