FIND

From LongJump Support Wiki

The FIND function returns the starting character number of a search string within a specified target string. Optionally, a character number can be specified, which defines the character from which to start. If the character number is not specified, then the search starts from the first character of the string.

Syntax
FIND(string, searchString, start)
Return
Number
Example
FIND('street', '123 Maple Street') = 11