Unix 网络编程基础----网络字节序（大端小端）

什么是字节序?

0x1122

主机字节序判断方法

1. 使用union:

[code]#include<iostream>

using namespace std;

int main()
{
    union {
        short s;
        char c[sizeof(short)];
    } un;

    un.s = 0x1122;

    if(sizeof(short) == 2)
    {
        if(un.c[0] == 0x11 && un.c[1] == 0x22)
            cout << "Big Endian" << endl;
        else if(un.c[0] == 0x22 && un.c[1] == 0x11)
            cout << "Little Endian" << endl;
        else
            cout << "unknown" << endl;

    }
    //c[0]为低地址，c[1]为高地址，11为高八位，22为低八位

    else
        cout << "short size: " << sizeof(short) << endl;

    return 0;
}

Little Endian

2. 使用指针的强制类型转换

[code]#include<iostream>
#include<iomanip>
using namespace std;

template<typename t> void showBytes(t &x)
{
    int len = sizeof(t);
    unsigned char* ptr = reinterpret_cast<unsigned char*>(&x);
    //cout << len << endl;
    cout << "0x";
    for(int i(0); i != len; ++i)
    {
        cout << setw(2) << setfill('0') 
             << hex << static_cast<int>(ptr[i]) << flush;
    }
    cout << endl;
}

int main()
{
    short val = 0x1122;
    showBytes(val);
    return 0;
}

0x2211