#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;}