union

/*************************************************************************
    > File Name: helloC++.cpp
    > Author: ma6174
    > Mail: [email protected] 
    > Created Time: Fri 27 Jun 2014 10:36:49 PM WST -pthread
    > Compile g++ -std=c++11 -g -o hello helloC++.cpp -pthread -lpthread
 ************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <limits.h>
#include <iostream>
#include <map>
#include <list>
#include <thread>
#include <exception>
#include <future>
#include <chrono>
#include <condition_variable>
#include <mutex>
#include <memory>
using namespace std;
using namespace std::chrono;
inline bool IsLittleEndian()
{
    static union
    {
        char ch[4];
        unsigned long b;
    }Test = {'1', '?', '?', '2'};
    return '1' == (char)Test.b;

}
typedef struct T0
{
    int a;
}T0;
typedef struct T1
{
    char b;
}T1;
typedef union
{
    T0 t0;
    T1 t1;
}T;
typedef struct  TPack
{
    char type;
    T t;
}TPack;
void fun()
{
    TPack pack;
    pack.type = '0';
    pack.t.t0.a = 10;
}
int main() 
{
    cout << IsLittleEndian() << endl;


    return 0;
}