C函数库中的strcmp实现

/**copyright@nciaebupt 转载请注明出处*原型：int strcmp(const char *s1,const char * s2);*用法：#include <string.h>*功能：比较字符串s1和s2。*说明：*   当s1<s2时，返回值<0*   当s1=s2时，返回值=0*   当s1>s2时，返回值>0*使用C函数库中的strcmp*/#include <cstdio>#include <cstring>int main(int args,char ** argv){    char str1[] = "apple";    char *str2 = "apple";    int flag = strcmp(str1,str2);    if(flag < 0)    printf("%s is less than %s\n",str1,str2);    else if(flag == 0)  printf("%s is equal %s\n",str1,str2);    else    printf("%s is larger than %s\n",str1,str2);    getchar();    return 0;}/**copyright@nciaebupt 转载请注明出处*原型：int strcmp(const char *s1,const char * s2);*用法：#include <string.h>*功能：比较字符串s1和s2。*说明：*   当s1<s2时，返回值<0*   当s1=s2时，返回值=0*   当s1>s2时，返回值>0*自己是实现strcmp*/#include <cstdio>int _strcmp(const char * src,const char * dest){    int ret = 0;    while(!(ret = *(unsigned char *)src - *(unsigned char *)dest) && *dest)    {        src++;        dest++;    }    if(ret < 0) ret = -1;    else if(ret > 0) ret = 1;    return ret;}int main(int args,char ** argv){    char str1[] = "apPle";    char *str2 = "apple";    int flag = _strcmp(str1,str2);    if(flag < 0)    printf("%s is less than %s\n",str1,str2);    else if(flag == 0)  printf("%s is equal %s\n",str1,str2);    else    printf("%s is larger than %s\n",str1,str2);    getchar();    return 0;}