/* return a pointer to the first occurrence of needle in haystack (if none, return NULL) */ char *strstr(char *haystack, char *needle); haystack - N needle - K

substr.py

def strstr(haystack, needle):
    for i in range(len(haystack) - len(needle) + 1):
        match = True
        for j in range(len(needle)):
            if haystack[i+j] != needle[j]:
                match = False
                break
        if match == True: return i
    return None