How to convert a Unix epoch time to a Pascal TDateTime(double) in C++

Question

Following on from this Original post I need to do the conversion in the reverse direction (Unix Time to TDateTime).

@Howard Hinnant did a very elegant example using his date.h library but due to a compilation issue, I decided not to use it. His effort is appreciated though.

Could someone provide me with an example based on the code developed by @Remy Lebeau, please?

Answer 1

This direction is easier than the other one. Here is a way:

#include <stdio.h>

double UnixToDateTime(__int64 epoch)
{
    int days = epoch / (24*3600);
    int secs = epoch % (24*3600);
    return 25569 + days + ((double)secs)/(24*3600);
}

int main()
{
    printf("%.12f", UnixToDateTime(1060041720));
}

Output:

37838.001388888886