C函数库中的memcmp实现

/**copyright@nciaebupt 转载请注明出处*原型：int memcmp(const void *buf1, const void *buf2, size_t count);*用法：#include <string.h>*功能：比较内存区域buf1和buf2的前count个字节。*说明：*   当buf1<buf2时，返回值<0*   当buf1=buf2时，返回值=0*   当buf1>buf2时，返回值>0*使用C函数库中的memcmp*/#include <cstdio>#include <cstring>int main(int args,char ** argv){    char str1[] = "Hello World!";    char str2[] = "Hello world!";    int flag = memcmp(str1,str2,sizeof(str1));    if(flag < 0)    printf("%s is less than %s\n",str1,str2);    else if(flag == 0)  printf("%s is equal %s",str1,str2);    else    printf("%s is larger than %s",str1,str2);    getchar();    return 0;}/**copyright@nciaebupt 转载请注明出处*原型：int memcmp(const void *buf1, const void *buf2, size_t count);*用法：#include <string.h>*功能：比较内存区域buf1和buf2的前count个字节。*说明：*   当buf1<buf2时，返回值<0*   当buf1=buf2时，返回值=0*   当buf1>buf2时，返回值>0*自己实现memcmp*/#include <cstdio>int _memcmp(const void * buf1,const void * buf2,size_t count){    if(!count)        return 0;    while(count-- && *((char *)buf1) == *((char *)buf2))    {        buf1 = (char *)buf1 + 1;        buf2 = (char *)buf2 + 1;    }    return (*((char *)buf1)-*((char *)buf2));}int main(int args,char ** argv){    char str1[] = "Hello World!";    char str2[] = "Hello world!";    int flag = _memcmp(str1,str2,sizeof(str1));    if(flag < 0)    printf("%s is less than %s\n",str1,str2);    else if(flag == 0)  printf("%s is equal %s",str1,str2);    else    printf("%s is larger than %s",str1,str2);    getchar();    return 0;}