/**原型：int strcmp(const char *s1,const char * s2);*用法：#include 
     
      *功能：比较字符串s1和s2。*说明：*   当s1
      
       <0*   当s1=s2时，返回值=0*   当s1>s2时，返回值>0*编程实现strcmp*/#include 
       
        #include 
        
         int _strcmp(const char * s,const char * t){    assert((s != NULL)&&(t != NULL));    while(*s && *t && *s==*t)    {        s++;        t++;    }    return *s-*t;}int main(){    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;}