Decimal/double to integer - round up (not just to nearest)

Question

How would you round up a decimal or float to an integer. For instance...

0.0 => 0
0.1 => 1
1.1 => 2
1.7 => 2
2.1 => 3

Etc.

What behaviour do you want for negative numbers? does -1.1 go to -1 (go to larger) or -2 (go to farther from zero)? — Eric Lippert, Dec 29 '11 at 16:25

score 58 · Accepted Answer · answered Dec 29 '11 at 09:37

58

Simple, use Math.Ceiling:

var wholeNumber = (int)Math.Ceiling(fractionalNumber);

answered Dec 29 '11 at 09:37

George Duckett

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I know it's off-topic, but may I ask you why you used `var` and not `int`? – ken2k Dec 29 '11 at 09:56
3

Purely out of habit. `var` can be useful when declaring objects of a longer type like `var myDictionary = new Dictionary>()` for example. – George Duckett Dec 29 '11 at 09:57

score 5 · Answer 2 · answered Dec 29 '11 at 09:39

5

Something like this?

int myInt = (int)Math.Ceiling(myDecimal);

answered Dec 29 '11 at 09:39

Øyvind Bråthen

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Why convert to a string only to parse back? Just cast it. – George Duckett Dec 29 '11 at 09:40

Mohsen Abdollahi · Answer 3 · 2014-10-18T18:03:52.407

Math.Ceiling not working for me, I use this code and this work :)

int MyRoundedNumber= (int) MyDecimalNumber;
                if (Convert.ToInt32(MyDecimalNumber.ToString().Split('.')[1]) != 0)
                    MyRoundedNumber++;

and if you want to round negative number to down for example round -1.1 to -2 use this

  int MyRoundedNumber= (int) MyDecimalNumber;
                    if (Convert.ToInt32(MyDecimalNumber.ToString().Split('.')[1]) != 0)
                        if(MyRoundedNumber>=0)
                           MyRoundedNumber++;
                        else
                           MyRoundedNumber--;

This is a horrible approach. Convert to string, seriously? – mafu Mar 19 '22 at 19:41 — mafu, Mar 19 '22 at 19:41

score 0 · Answer 4 · answered May 16 '17 at 14:38

0

Before saying it does not work, you have to check that ALL VALUES in the operation are double type. Here is an example in C#:

 int speed= Convert.ToInt32(Math.Ceiling((double)distance/ (double)time));

answered May 16 '17 at 14:38

Manuel Roldan

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score -1 · Answer 5 · edited Mar 24 '16 at 07:51

-1

var d = 1.5m;
var i = (int)Math.Ceiling(d);
Console.Write(i);

edited Mar 24 '16 at 07:51

Vadim Martynov

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answered Mar 23 '16 at 14:14

ali karaca

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This just *rounds* the number, it doesn't necessarily round it **up**. – radoh Mar 23 '16 at 14:39

Decimal/double to integer - round up (not just to nearest)

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