2.14.21 strstr
Declaration:
char *strstr(const char *str1, const char *str2);
Finds the first occurrence of the entire string str2 (not including the terminating null character) which appears in the string str1.
Returns a pointer to the first occurrence of str2 in str1. If no match was found, then a null pointer is returned. If str2 points to a string of zero length, then the argument str1 is returned.