memchr ( )【C语言库函数源代码】

【C语言库函数源代码】

【本程序在Dev C++ 4.9.9.2 下编译通过】

#include

/*

   Searches at bufferfor the given character, stopping when characteris first found or cnt bytes have been searched through.

   从buffer所指内存区域的前count个字节查找字符ch，当第一次遇到字符ch时停止查找。如果成功，返回指向字符ch的指针；否则返回NULL。

*/

 

void * my_memchr(const void * buffer,int ch,int count)

{

   while ( count && (*(unsigned char *)buffer != (unsigned char)ch) )

   {

      buffer = (unsigned char *)buffer + 1;

        count--;

   }

   return(count ? (void *)buffer : NULL);

}

int main()

{

   char *str = "ammana_babi";

   char * p;

   char ch;

  

   ch = '9';

   p = (char *)my_memchr(str,ch,strlen(str)+1);

   if(p == NULL)

      printf("Can't find the character %c !\n",ch);

   else

      printf("Find the character %c !\n",*p);

  

   ch = 'b';

   p = (char *)my_memchr(str,ch,strlen(str)+1);

   if(p == NULL)

      printf("Can't find the character %c !\n",ch);

   else

      printf("Find the character %c !\n",*p);

 

   system("pause");

   return 0;

}