Why does dividing a float by an integer return 0.0?

java math division integer-division
Arif Driessen picture Arif Driessen · Sep 23, 2010 · Viewed 49.9k times · Source

So if I have a range of numbers '0 - 1024' and I want to bring them into '0 - 255', the maths would dictate to divide the input by the maximum the input will be (1024 in this case) which will give me a number between 0.0 - 1.0. then multiply that by the destination range, (255).

Which is what I want to do!

But for some reason in Java (using Processing) It will always return a value of 0.

The code would be as simple as this

float scale;
scale = (n/1024) * 255;

But I just get 0.0. I've tried double and int. all to no avail. WHY!?

Answer

tim_yates picture tim_yates · Sep 23, 2010

It's because you're doing integer division.

Divide by a double or a float, and it will work:

double scale = ( n / 1024.0 ) * 255 ;

Or, if you want it as a float,

float scale = ( n / 1024.0f ) * 255 ;

Related questions

How do I divide so I get a decimal value?

I want to know how to get remainder and quotient in single value in Java. Example: 3/2 I should get value as 1.5. If I use the / operator I get only the quotient. If I user the % operator I get only the …

Read More
Integer division in Java

This feels like a stupid question, but I can't find the answer anywhere in the Java documentation. If I declare two ints and then divide them, what exactly is happening? Are they converted to floats/doubles first, divided, then cast …

Read More
Java - How to check if a division is an integer or a float?

Couldnt think of a better title. Well the problem is: I have the "int i", it can be any value. my goal is to transform the "int i" to the closest number divisible by 16. For example, I got i = 33. Then …

Read More