how to search for specific part of tring c# code example

Example 1: letter at index of string c#

string s = "hello";
char c = s[1];
// now c == 'e'

Example 2: how to look for substring in string in c#

String phrase = "this is the ultimate string";

Console.WriteLine(phrase.Contains("this")); //returns True
Console.WriteLine(phrase.Contains("python")); //returns False