Division

The reason that we didn’t cover division in the main arithmetic operators chapter is that division behaves a little differently depending on the data types of the values being divided.

Floating-point division

If we’re working with float or double values, division behaves as you’d expect:

double result = 7.0 / 2.0; // 3.5
float result2 = 5.5f / 2.0f; // 2.75f

These results are the same as what you’d get from a calculator.

Note that, because of how floating-point numbers are represented in binary, you may sometimes get results that are very slightly off from what you’d expect.
For example, 0.1 + 0.2 may evaluate to 0.30000000000000004 instead of 0.3. That is perfectly normal, but can cause some unexpected behaviour if you’re not aware of it! You should always use ‘loose equality’ when working with floats

Integer division

Integer division is a little different.

Instead of giving us a decimal result, integer division truncates the decimal part and only gives us the whole number part of the result.

For example, you may thing that 7 / 2 would evaluate to 3.5, but because we’re using integers, the result is truncated to just 3. Remember that truncation isn’t rounding, but rather ‘chopping off’ the decimal part entirely:

int result = 7 / 2; // 3.5 -> 3
int result2 = 5 / 3; // 1.666... -> 1

If you want to get a decimal result from dividing two integers, you need to cast one (or both) of the integers to a floating-point type first:

int a = 7;
int b = 2;
double result1 = (double)a / b; // 3.5
double result2 = a / (double)b; // 3.5
double result3 = (double)a / (double)b; // 3.5