using union struct jundge big or little endian

大端小端其实就是字节顺序。

以一个32位的整数为例0x12345678,该整数地址为0x400000000.

地址	大端	小端
0x400000000	0x12	0x78
0x400000001	0x34	0x56
0x400000002	0x56	0x34
0x400000003	0x78	0x12

速记：
小小小 - 小端 小地址 存小数(低位的值)

/*****
> File Name: endian.c
> Author: Lin
> Mail: [email protected]
> Created Time: Tue Aug 6 15:36:27 2019
****/

#include <stdio.h>

int main()
{
union
{
int i;
char ch;
}endian_un;
endian_un.i = 1;
if(endian_un.ch == 1)
printf(“The Host is little endiann”);
else
printf(“The Host is big endiann”);
}