Question

I am asking the user to input a start time and an end time in this format: 15.45 (military time with a decimal instead of a colon) and I need to convert those times to a float to perform calculations on them. I am having trouble wrapping my mind around converting the 60 minutes of an hour to a decimal value. e.g. – User inputs start of 12.45 and end of 14.15, this should be converted to 12.75 and 14.25 respectively. How would I go about this conversion?

Also, something I believe I am more capable of figuring out, but curious anyway: how would I validate input so as not to allow a time greater than 23.59 and no time with the last two digits greater than 59?

Answer 1

As soon as one of the values is double, then the arithmetic will be
done in double, with double results. So you can convert the
minutes to double, using any of the three C++ syntaxes:
static_cast<double>(minutes), double(minutes) or (double)minutes,
or just divide by 60.0, rather than the integer 60. (I like to be
explicit, so I’d write double(minutes) / 60.0. And some people prefer
static_cast, even in this case.)

With regards to the validation, I’d do it before conversion; once you’ve
added the minutes to the hours, it’s too late anyway.