Is there way of stopping uint underflow in C#?

Question

Use int to test if below 0 . uint in c# wraps around to a huge number once it goes below 0, this is in all programming languages.

Why not check if your uint is bigger than the number you're subtracting before you subtract it? If it isn't, set your uint to 0. — ProgrammingLlama, Sep 29 '18 at 05:22
One of the most useful and most overlooked build options is Project > Properties > Build tab > Advanced button, "Check for arithmetic overflow/underflow". Ideal in the Debug configuration and ideally suited to remind you to write the code to stop underflow where necessary. — Hans Passant, Sep 29 '18 at 10:35

score 4 · Answer 1 · answered Sep 29 '18 at 03:56

4

You can do it like this

uint i = 0;
i = checked(i - 1);

This will throw System.OverflowException. Though it will not stay zero, at least you will be sure that no overflow happened.

answered Sep 29 '18 at 03:56

Yola

I didn't want this this way, it will slow down my app too much. – user366866 Oct 13 '18 at 01:21

score -2 · Answer 2 · answered Sep 29 '18 at 03:51

-2

I just use ordinary int instead of uint, and check if its < 0... problem solved

answered Sep 29 '18 at 03:51

user366866

2

Considering you are answering your own question (which generally isn't a problem), _why_ did you pick `uint` in the first place. Surely it was for the positive range. I feel this question-answer pair isn't useful – Sep 29 '18 at 04:35
i thought if uint goes below 0 it stays 0 – user366866 Sep 29 '18 at 04:37
...and if you decrement an `int` value of `-2,147,483,648` it suddenly wraps round to `2,147,483,647` and vice versa. These are all symptoms of how integer values are stored in binary – Sep 29 '18 at 04:41

2 Answers2