#include <iostream>
#include <ctime>
using namespace std;
int main()
{
    cout << sizeof(long) << endl;//4
    cout << sizeof(long long) << endl;//8
    cout << sizeof(__int64) << endl;//8
    //time_t在64位上为__time64_t，为__int64与long long相似，在32位上为long
    //time(0)返回的是系统的时间（从1970.1.1午夜算起），单位：秒
    time_t t = time(0);
    printf("%I64d", t);//%I64u对应unsigned __int64，%lld对应long long,%llu对应unsigned long long
    getchar();
    return 0;
}