How to find the difference between two timestamps

Question

I'm using this time library to access the properties of unix timestamps like hours / minutes / etc. What I want to do is get the current time, and an estimated arrival time, and find the difference between them in minutes.

Here's my code: (My estimated time is coming from an API as an INT)

time_t timeEstimated = timeInt;
time_t timeNow = now();

But how do I find the difference between these two timestamps in minutes? I'd like to try and avoid all of the conditionals / math that would come with converting to hours / minutes / seconds / dates and subtracting each component if possible.

Answer 1

Unix timestamps are just a count of seconds since a standard origin (1970.0 UTC), thus a simple subtraction, followed by a conversion from seconds to minutes:

float minutes_remaining = (timeEstimated - timeNow) / 60.0;