实现找子串的编程

#include <iostream>#include <cstring>using namespace std;const char *  my_strstr(const char *s1,const char *s2){    const char *bp;    const char *sp;    if( s1 == NULL || s2 == NULL)    {        return NULL;    }    while(*s1)    {        bp = s1;        sp = s2;        //*号和++是单目运算符，优先级相同，但是结合方向是从右至左。        //就是把*号右面的看成一个整体，也就是*(a++)=*(b++); 因为++在后，所以最后做增1，先做*（a）=*(b), 然后b++, a++;        while(*bp++ == *sp++)//*bp *sp -> *bp == *sp ,a++,b++;        {            if(!*sp)//sp = 0;            {                return s1;            }        }        s1++;    }    return NULL;    /*    while(*s1 != '\0')    {        if(strncmp(s1,s2,len) == 0)        {            return int(s1);        }        s1++;    }    */    return 0;}int main(){    char str[100];    char ptr[100];    cout << "Please input str and str" << endl;    cin.getline(str,100);    cin.getline(ptr,100);    const char *ret = my_strstr(str,ptr);    if(ret == 0)    {        cout <<"No found" << endl;    }    else    {        cout << "ret = " << (int *)ret << endl;        cout << "Found" << endl;    }    return 0;}