C++ 已知两个时间（年月日）求日期差

转载：https://blog.csdn.net/flyyufenfei/article/details/79796035

#include<iostream>
#include <ctime>  

using namespace std;  

int main() {
    struct tm t1 = {  };
    struct tm t2 = {  };
    double seconds;  

    t1.tm_year =  - ; t1.tm_mon = ; t1.tm_mday = ;//现在时间2019,7,6
    t2.tm_year =  - ; t2.tm_mon = ; t2.tm_mday = ;//明年高考时间2020,6,7  

    seconds = difftime(mktime(&t2), mktime(&t1));//转换结构体为time_t,利用difftime,计算时间差  

    cout << seconds /  << endl;//最后输出时间,因为一天有86400秒(60*60*24)
    system("pause");
    return ;
}