CODEWITHSUNDEEP
c#doublescale
Younes
Younes

Reputation: 4823

Division in c# not going the way I expect

Im trying to write something to get my images to show correctly. I have 2 numbers "breedtePlaatje" and "hoogtePlaatje". When i load those 2 vars with the values i get back "800" and "500" i expect "verH" to be (500 / 800) = 0,625. Tho the value of verH = 0..

This is the code:

int breedtePlaatje = Convert.ToInt32(imagefield.Width);
int hoogtePlaatje = Convert.ToInt32(imagefield.Height);

//Uitgaan van breedte plaatje
if (breedtePlaatje > hoogtePlaatje)
{
    double verH = (hoogtePlaatje/breedtePlaatje);
    int vHeight = Convert.ToInt32(verH * 239);

    mOptsMedium.Height = vHeight;
    mOptsMedium.Width = 239;

    //Hij wordt te klein en je krijgt randen te zien, dus plaatje zelf instellen
    if (hoogtePlaatje < 179)
    {
        mOptsMedium.Height = 179;
        mOptsMedium.Width = 239;
    }
}

Any tips regarding my approach would be lovely aswell.

Upvotes: 6

Views: 14965

Answers (6)

Harry Smith
Harry Smith

Reputation: 79

C sharp divides integers like a child. Throwing away any leftover fractional part. Simply cast the denominator as a double or a float and it will work the way you expect. When you divide by a constant integer remember to put a .0 after the integer to make it a double.

Upvotes: 0

Greg Beech
Greg Beech

Reputation: 136627

When you divide two integers, C# uses integer division, where the fractional part is discarded. In your case you're getting:

500 / 800 = 0 + 5/8

Which, discarding the fractional part, gives:

500 / 800 = 0

To get floating point division, cast one of the arguments to either double, float or decimal depending on the level of precision you need, which will cause the other argument to be implicitly converted to the same type and the division carried out using floating point rules instead of integer rules, e.g.

double result = (double)breedtePlaatje  / hoogtePlaatje ;

Upvotes: 4

Tarydon
Tarydon

Reputation: 5183

Try this:

double verH = double (hoogtePlaatje) / breedtePlaateje;

If you divide an int by an int, you will get a truncated answer. Cast one of them up to a double, and the entire division will be done as double.

Upvotes: 1

Oded
Oded

Reputation: 499002

Integer division will result in an Integer being returned as the division result.

You need one of the parameters of the division to be a float in order for the result to be a float. You can do this by casting one of them to a float.

double verH = (double)hoogtePlaatje/breedtePlaatje;

Or

double verH = hoogtePlaatje/(double)breedtePlaatje;

See the C# spec regarding division.

Upvotes: 7

kd35a
kd35a

Reputation: 121

I have never used C#, but probably you will need to cast one of the variables to double, like this:

double verH = (double)hoogtePlaatje/breedtePlaatje;

Upvotes: 2

Arve
Arve

Reputation: 7506

Dividing int by int gives an int.

double verH = (hoogtePlaatje/breedtePlaatje);

The right hand side of the assignment is an integer value.

Change breedtePlaatje and/or hoogtePlaatje to double and you will get the answer you expect.

Upvotes: 11

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