strstr(模拟实现与介绍)

模拟实现

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<assert.h>
char* my_strstr(const char* str1, const char* str2)
{
  assert(str1 && str2);
  if (*str2 == '\0')
  {
    return (char*)str1;
  }
  const char* s1 = str1;
  const char* s2 = str2;
  const char* cp = str1;
  while (*cp)
  {
    s1 = cp;
    s2 = str2;
    while (*s1 != '\0' && *s2 != '\0' && *s1 == *s2)
    {
      s1++;
      s2++;
    }
    if (*s2 == '\0')
    {
      return (char*)cp;
    }
    cp++;
  }
  return NULL;
}
int main()
{
  char arr1[] = "abbbcdef";
  char arr2[] = "bbc";
  char* ret = my_strstr(arr1, arr2);
  if (ret == NULL)
  {
    printf("找不到\n");
  }
  else
  {
    printf("%s\n", ret);
  }
  return 0;
}

介绍

该代码功能是，字符串的查找