Take 4 places after decimal for a double variable

Question

I dont want to round I want to take 4 places after decimal.

Example:

double something = 0.00038;

I want the result to be

0.0003   // 8 is discarded

how can I achieve that?

Are you using this for a display, or do you need to number for mathematical calculations? — Mike Precup, Aug 28 '13 at 14:30

score 5 · Accepted Answer · edited Aug 28 '13 at 14:25

5

double result = Math.Truncate(10000 * something) / 10000;

edited Aug 28 '13 at 14:25

Soner Gönül

answered Aug 28 '13 at 14:25

Karl Anderson

1

@MikePrecup's comment on the answer using `float` applies here as well... better to use Decimal – PinnyM Aug 28 '13 at 14:29

Logan Murphy · Answer 2 · 2013-08-28T15:13:46.637

1

Just multiply, truncate, then divide.

decimal f = 100.0123456;
f = Math.Truncate(f * 10000) / 10000;

Here is a nice little function you can use

public static decimal MyTruncate(decimal input, int digit) {
    return Math.Truncate(input * Math.Pow(10, -digit)) / Math.Pow(10, -digit);
}

this function truncates anything to the right of the specified digit

where 0 is the ones place, 1 is the tens place and -1 is the tenths place

edited Aug 28 '13 at 15:13

answered Aug 28 '13 at 14:25

Logan Murphy

Using `float` could lead to results like 0.000299999999999 – Mike Precup Aug 28 '13 at 14:27
@MikePrecup which data type do you suggest? – Logan Murphy Aug 28 '13 at 14:27
1

`Decimal` would prevent that. – Mike Precup Aug 28 '13 at 14:28
`MyTruncate` never uses `input`. – Mike Precup Aug 28 '13 at 14:44
@MikePrecup lol would you look at that...thanks, EDIT MADE – Logan Murphy Aug 28 '13 at 14:58

2 Answers2