CODEWITHSUNDEEP
c#
Christian Frantz
Christian Frantz

Reputation: 253

Math.Round problems

I'm trying to create a clock for my game. My hours and seconds are both float values so I am using Math.Round to round them off to the nearest whole number. The problem is that the Hours and Seconds variables aren't changing at all. Am I using Math.Round wrong?

public void Update()
    {
        Hours = (float)Math.Round(Hours, 0);
        ClockTime = Hours + ":" + Seconds;
        if (Hours >= 24)
            Hours = 0;
        if (Seconds >= 60)
            Seconds = 0;
    }

In my update method for my day/night class.

        float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds;

        clock.Hours += (float)elapsed;
        clock.Update();

When I print the numbers on the screen, nothing is changing. If I take away the (float) cast to the Math.Round I get an error cannot convert double to float.

Upvotes: 0

Views: 236

Answers (2)

paxdiablo
paxdiablo

Reputation: 881633

Don't use floating point in this case, there's absolutely no reason for an hour, minute or second to be non-integral.

What's almost certainly happening is that you're ending up with a float value like 59.9999 despite the fact you think you're rounding it.

There are real dangers in assuming floating point values have more precision than they actually do.

If you hold your number of seconds in an unsigned integral 32-bit type, you can represent elapsed time from now until about the year 2150 AD, should anyone still be playing your game at that point :-)

Then you simply use integer calculations to work out hours and seconds (assuming you're not interested in minutes as seems to be the case), pseudo-code such as:

hours = elapsed_secs / 3600
secs = elapsed_secs % 3600
print hours ":" seconds

Beyond that advice, what you're doing seems a tad strange. You are adding an elapsed seconds field (which I assume you're checked isn't always set to zero) to the hours variable. That's going to make gameplay a little difficult as time speeds by at three and a half thousand times its normal rate.

Upvotes: 3

Peter Huber
Peter Huber

Reputation: 3312

Actually, you should used DateTime to track your time and use the DateTime properties to get the hours and seconds correctly instead trying it yourself using float for seconds and hours. DateTime is long based and supports from fractions of milliseconds to millenias and of course seconds. It has all the functions built in to add milliseconds or years or seconds or ... correctly, which is actually rather difficult.

Upvotes: 0

Related Questions