函数实现:
信息来自RHEL,man page:
MEMCMP(3) Linux Programmer's Manual MEMCMP(3)
NAME
memcmp - compare memory areas
SYNOPSIS
#include <string.h>
int memcmp(const void *s1, const void *s2, size_t n);
DESCRIPTION
The memcmp() function compares the first n bytes (each interpreted as
unsigned char) of the memory areas s1 and s2.
RETURN VALUE
The memcmp() function returns an integer less than, equal to,