CODEWITHSUNDEEP
c#.net
Adam
Adam

Reputation: 3665

Rounding value to .5

There are the obvious quirks of Math.Round but is there a way to make Math.Round fulfill this type of manipulation for a rating system.

If greater than .0 and less than or equal to .5, display half a star

If greater than .5 and less than or equal to .0 display whole star

So obviously a half star would be .5 and a whole start would be the next whole value.

I don't know of a rounding method to go to half whole numbers.

Should I just write if statements to control my rounding?

**Edit/Solution

From the below answer I came up with.

double roundedRating = (Math.Ceiling(2 * currentRating)) / 2;

Upvotes: 1

Views: 2340

Answers (5)

matt3141
matt3141

Reputation: 4423

I'd recommend multiplying by two, performing Math.Ceiling, and dividing by two to get to the nearest half.

Upvotes: 17

codingbiz
codingbiz

Reputation: 26386

Can this work?

Multiply the number by 10 e.g. 0.1x10, 0.2x10 to get n

Math.Ceil(n / 5) / 2 
where n = 1, 2, 3 instead of - .1, .2, .3

examples:

1,2,3,4,5 = 1/2 = 0.5
6,7,8,9,10 = 2/2 = 1
11,12,13,14,15 = 3/2 = 1.5

Upvotes: 1

Eren Ersönmez
Eren Ersönmez

Reputation: 39085

double roundedRating = (int)(currentRating * 2D + 0.999999999999999) / 2D

Upvotes: 0

BlackVegetable
BlackVegetable

Reputation: 13054

If efficiency is no issue, the following approach could be used:

Number *= 10;
Number % 10 = remainder;
if(remainder <=5 && remainder != 0)
  //Half star
else
  //Whole star

However, that code is kinda ugly, but I think it gives you the general idea.

Upvotes: 0

Nick Vaccaro
Nick Vaccaro

Reputation: 5504

You're going to want to make sure that you end up performing your checks against integers, rather than floating point numbers.

Start by multiplying the number by 2. Continue doing this until it's an integer value (no value in the decimal part).

Now, continuously divide by 2 until you end up with a number that's less than or equal to the original number. If the result decimal part is greater than .0 and less than or equal to .5, display half a star. If it's greater than .5 and less than or equal to +.0, display a whole star.

Actually, go with matt's answer. ; )

Upvotes: 2

Related Questions