c 判断大段字节序小段字节序

这里使用联合和指针两种方法

#include 

void is_lsb(void);
void is_lsb1(void);

int main()
{
    is_lsb();
    is_lsb1();
    return 0;
}


void is_lsb(void)
{
    union u_data
    {
        unsigned char a;
        unsigned int b;
    }data;

    data.b=0x12345678;
    printf("data size is %ldn",sizeof(data));
    printf("b=%xn",data.b);
    printf("a=%xn",data.a);
    if(data.a==0x78)
    {
        printf("the os is LSBn");
    }
    else if(data.a==0x12)
    {
        printf("the os is MSBn");
    }
    else
    {
        printf("wrongn");
    }
}

/使用指针来判断大端字节序还是小段字节序/
void is_lsb1(void)
{
    unsigned int a=0x12345678;
    unsigned char *p;
    p=(unsigned char *)&a; 
    printf("*p=%xn",*p);
    if(*p==0x78)
    {
        printf("os is lsbn");
    }
    else if(*p==0x12)
    {
        printf("os is msbn");
    }
    else
    {
        printf("wrongn");
    }
}

输出结果