strstr实现

自己实现的很不好：

char* str_str(const char* s1,const char* s2){assert(s1 != NULL && s2 != NULL);while(*s1++ != '\0'){if(strncmp(s1,s2,strlen(s2))==0){return (char*)s1;}}return NULL;}

另一个版本VC++2005：

char *strstr (const char * str1, const char * str2){    char *cp = (char *) str1;    char *s1, *s2;    if( !*str2 )        return((char *)str1);    while(*cp)    {          s1 = cp;          s2 = (char *) str2;          while ( *s1 && *s2 && !(*s1-*s2) )                s1++, s2++;          if (!*s2)                return(cp);          cp++;    }    return (NULL);}

Do not complain about things you are not willing to work hard to change.