var is casted to int even when result should be decimal

Question

I know this is a really basic question, but please explain why this is.

var number = 7 / 2; // number is 3
decimal number = 7 /2; // still number is 3

Why isn't the number 3.5? Why is it always casted to int? Because the numbers are both int? This works when you cast one of the numbers to decimal.

You are dividing two integers, the result is always an integer. — Steve, Aug 30 '16 at 12:45
The denominator is 2 (change to 2.0) so the compiler truncates the fraction part of the results. — jdweng, Aug 30 '16 at 12:45
The expression *7 / 2* (type `int` / `int`) will evaluate to the integer value 3 as it is using integer division. — Raktim Biswas, Aug 30 '16 at 12:50
If you want a numeric literal to be treated as decimal, use the suffix `m` after one of the numbers that you're dividing (just as Rene and Manfred have pointed out) — Grizzly, Aug 30 '16 at 12:51

score 7 · Accepted Answer · answered Aug 30 '16 at 12:46

The literals 7 and 2 both are interpreted by the compiler as int. So the division is an integer division resulting in an int of value 3.

Using the var keyword, the compiler infers the correct type from the expression, leading to number in the first line being of type int.

In the second line, you explicitly declare number as decimal, so the int returned by 7 / 2 is casted to decimal.

If you want the result to be decimal, you should use the correct literal ending with m:

var number = 7/2m;

score 3 · Answer 2 · answered Aug 30 '16 at 12:46

3

Because 7/3 is (int)7/(int)3. If you want to get a decimal, use 7m/2m

answered Aug 30 '16 at 12:46

Manfred Radlwimmer

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it's enough to do `7/2m` – Gilad Green Aug 30 '16 at 12:46
@GiladGreen yep, that would suffice. – Manfred Radlwimmer Aug 30 '16 at 12:47
@GiladGreen or `7m/2` – slawekwin Aug 30 '16 at 12:47

var is casted to int even when result should be decimal

2 Answers2