strpos() function
Return the index of a regular expression in a string.
Syntax
strpos(haystack, needle)
Returns -1 if the expression isn't found.
Arguments
haystack → is string. The string that is to be searched.
needle → is string. The regular expression to look for.
Example
strpos('HELLO WORLD','WORLD') → 6
strpos('HELLO WORLD','GOODBYE') → -1