instr - search for pattern in string
short instr(n, s, t)
struct string *s, *t;
Instr returns the location of the first occurrence of the string
pointed to by t in the string pointed to by s starting
with location n. Locations are numbered starting with one.
If the string pointed to by t is the null string, n
This function implements the BASIC INSTR function.
Error 5 (Illegal function call) is generated if n is non-positive.
Instr returns zero if the search fails or if location n
lies beyond the end of the string pointed to by s.
The Basmark QuickBASIC Programmerís Manual