getting 0 with a division into a float type

[Rick]

OK, feeling dumb. What am I missing with this. The following is setting ratio to 0.0 instead of 0.25.

 

 

float ratio = 200 / 800;

[Paul]

Because its an integer division. Try 200.0f / 800.0f

[Mumbles]

Because its an integer division. Try 200.0f / 800.0f

 

Well, that's the fastest solution.

 

 

float a = 200, b = 800, ratio = a / b;

 

would also work because by the time 'a' and 'b' are reached they are floats. In Rick's case it evaluates the constants (as ints) as 0 and then stores the result as ratio

[Rick]

I could have sworn at one point in C++ it would do the conversion for me, but maybe I've been using .NET to long. Thanks guys.

[Roland]

The compiler just needs a little hint on whats going on.

So this will do the trick

 

float ratio = 200.0 / 800; 

 

ration will get the value 0.25 as excepted.

[Rick]

Yeah I was just using those as hardcoded examples. In the actual code those are variables that are from TextureWidth/Height functions. I casted them both to float and they work now. I could have sworn it used to know that.

[Canardia]

If you use double instead of float, you get 5 times faster speed (you can verify it with GNU/VS2008 by timing the execution of a few float vs double calculations):

double ratio = 200.0 / 800.0;