判断大端小端模式

代码如下：

big_little_endian.c

#include <stdio.h>

#define BIG_ENDIAN     1
#define LITTEL_ENDIAN  0

int big_littel_endian(void)
{
    union num
    {
        int a;
        char b[4];
    }c;
    
    c.a = 0x1234;
    
    if(c.b[0] == 0x34)
    {
        return LITTEL_ENDIAN;
    }
    else
    {
        return BIG_ENDIAN;
    }
    
}

int main()
{
    int cpu;
    
    cpu = big_littel_endian();
    
    if(cpu == LITTEL_ENDIAN)
        printf("cpu is Little_endian.
");
    else
        printf("cpu is Big_endian.
");
}

在Linux下编译：

gcc -o big_little_endian big_little_endian.c

运行：

./big_little_endian

输出结果：

cpu is Little_endian.