Round Up a double to int

Question

I have a number ("double") from int/int (such as 10/3).

What's the best way to Approximation by Excess and convert it to int on C#?

Uhm...maybe I don't know how to call it in english? :) Well, if you have 0.2->1; 0.8->1...and so on..."round" to the next int? — markzzz, Feb 15 '12 at 15:29

score 77 · Accepted Answer · answered Feb 15 '12 at 15:40

77

Are you asking about System.Math.Ceiling?

Math.Ceiling(0.2) == 1
Math.Ceiling(0.8) == 1
Math.Ceiling(2.6) == 3
Math.Ceiling(-1.4) == -1

answered Feb 15 '12 at 15:40

Doug McClean

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Math.Ceiling(-1.4)==-2 -- what language is that ? Tell me it's name so that I can shun it like the plague. – High Performance Mark Feb 15 '12 at 15:42
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Oops, I screwed that up. I looked it up, but I misread the example. – Doug McClean Feb 15 '12 at 15:44
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@HighPerformanceMark - well, in C# expression "Math.Ceiling(-1.4)==-2" is correct and basically returns false ;-) – Zegar May 27 '20 at 13:29
Seeing how Math.Ceiling returns a decimal and not an int, then no, but OP has accepted this as the answer anyway for some reason. – ataraxia May 28 '20 at 11:43

score 13 · Answer 2 · edited Sep 23 '16 at 00:37

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int scaled = (int)Math.Ceiling( (double) 10 / 3 ) ;

edited Sep 23 '16 at 00:37

Arne

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answered Feb 15 '12 at 15:41

EursPravus

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I think you need to cast it for this to work.. i.e. `int scaled = (int)Math.Ceiling( (double 10 / 3 );` – Mark Rhodes Mar 04 '14 at 09:58

score 2 · Answer 3 · answered Oct 06 '18 at 19:52

By "Approximation by Excess", I assume you're trying to "round up" the number of type double. So, @Doug McClean's "ceiling" method works just fine.

Here is a note: If you start with double x = 0.8; and you do the type conversion by (int)x; you get 0. Or, if you do (int)Math.Round(x); you get 1. If you start with double y = 0.4; and you do the type conversion by (int)y; you get 0. Or, if you do (int)Math.Round(y); you get 0.

score 0 · Answer 4 · answered Feb 15 '12 at 15:34

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Consider 2.42 , you can say it's 242/100 btw you can simplify it to 121/50 .

answered Feb 15 '12 at 15:34

mrbm

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Round Up a double to int

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