总结一下函数原型

strcpy函数的原型
1.strcpy的实现代码

char* strcpy(char* strDest,const char* strSrc)
{
   if((strDest == NULL) || (strSrc == NULL))

   throw "Invalid Arguments";

   char* strDestCopy = strDest;

   while((*strDest++ = *strSrc++) != '/0');
   return strDestCopy;
}
 

strlen函数实现:
int mystrlen(const char * str)
{
/*      int i = 0;
        while(*(str+i) != '/0')
                ++i;
        return i;*/

        assert( str != NULL );
        int len = 0;
        while( (*str++) != '/0' )
        {
                len++;
        }
        return len;

}

strcmp函数实现:
int mystrcmp(char * str1, char * str2)
{
        assert((str1 != NULL) && (str2 != NULL));

        int i, d;
        for (i = 0; str1[i] == str2[i]; i++)
                if (str1[i] == '/0')
                        return 0;

        d =  (str1[i]-str2[i])>0 ? (1) : (-1);
        return d;
}