Constant Pointer / structs

In my programming class, we have

struct Time {
    int hours, min, sec;
}

We are to create a method to compute the difference between two times:

Time *timeDiff(const Time *t1, const Time *t2)

I thought I could create the time开发者_开发问答 difference by getting everything in seconds, and then subtracting the two values, but it seems like extra work to do something like

long hour1 = t1->hours;
long min1 = t1->min;
long sec1 = t1->sec;

And then using these values to get the time in seconds, do something similar for the second time, and then subtract. Any thoughts? Thanks!

The way you've described it sounds exactly right. I might do something like

int sec = t1->sec + 60*(t1->min + 60*t1->hours);

Then similarly for t2, then subtract one from the other and break the result down into minutes and hours.