First index before a position

Question

I have a string and index in that string, and want to get the first position of a substring before that index.

e.g., in string:

\"this is a test string tha

Answer 1

Like IndexOf() where you can start, lastIndexOf also gives you a place to start from going backwards

var myString = "this is a test string that contains other string for testing";
var lastIndexOf = myString.LastIndexOf("string", 30);

Reports the zero-based index position of the last occurrence of a specified string within this instance. The search starts at a specified character position and proceeds backward toward the beginning of the string.