In c#, you can check if one string exists in another string using the contains method, the indexof method, or regular expressions. Here are examples of each approach: The contains () method checks whether the specified string is present in the string or not.

This code shows how to search within a string for a sub string and either returns an index position of the start or a -1 which indicates the string has not been found. You can also use contains(), contains is Ò€¦ Returns a value indicating whether a specified string occurs within this string, using the specified comparison rules.