C language--simulation to realize strcmp function

 First clarify the meaning of the function:

strcmp is a comparison function, and the function prototype is int strcmp(const char * src, const char * dst) The ASCIIZ value of the string is preferentially compared during the comparison process (compare from left to right until different characters or '/0' appear)

When src<dst, the return value is negative;

When src=dst, the return value is 0;

When src>dst, the return value is a positive number.

The code to implement the function is given below:

The first way:

char *my_strcmp(const char* src, const char* dst)
{
 assert(src);
 assert(dst);
 while (*src != '/0' && *dst != '/0' && *src = *dst)
 {
  src++;
  dst++;
  if (*src && *dst)
  {
   if (*src > *dst)
    return 1;
   else
    return -1;
  }
 }
  if (*src != '/0' && *dst != '/0' && *src == *dst)
   return 0;
  if (*src)
   return -1;
  if (*dst)
   return 1;
}

The second way:

char *my_strcmp(const char* src, const char* dst)
{
 int ret = 0;
 while (!(ret = *(unsigned char *)src - *(unsigned char *)dst) && *dst)
  ++src, ++dst;
 if (ret < 0)
  ret = -1;
 else if (ret > 0)
  ret = 1;
 return(ret);
}