#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string.h>
char* my_strstr(const char *p1,const char *p2)
{
assert(p1 != NULL);
assert(p2 != NULL);
char* s1 = p1;
char* s2 = p2;
char* cur = p1;
if (*p2 == '\0')
{
return p1;
}
while (*cur)
{
s1 = cur;
s2 = p2;
while ((*s2 != '\0') && (*s1!='\0') && (*s1 == *p2))
{
s1++;
s2++;
}
if (*p2 == '\0')
{
return cur;//找到字串
}
cur++;
}
return NULL;//找不到字串
}
int main()
{
char* p1 = "abcdef";
char* p2 = "def";
char* ret = my_strstr(p1, p2);
if (ret == NULL)
{
printf("字串不存在");
}
else
{
printf("%s\n", ret);
}
return 0;
}