The STRPOS function finds the first occurrence of a substring within an object string. If Search_String occurs in Expression , STRPOS returns the character position of the match, otherwise it returns -1.
The expression in which to search for the substring. If this argument is not a string, it is converted using IDL's default formatting rules. If Expression is an array, the result is an array with the same structure, where each element contains the position of the substring within the corresponding element Expression . If Expression is the null string, STRPOS returns the value -1.
The substring to be searched for within Expression . If this argument is not a string, it is converted using IDL's default formatting rules. If Search_String is the null string, STRPOS returns the smaller of Pos or one less than the length of Expression .