Limiting float to 4 decimal places

Question

This i what I am trying to achieve:

If a float has more than 4 decimal places, only keep until the first 4 dec places (do not round.)

Eg.: 111.3547698 -> 111.3547

If a float has less than 4 decimals, leave unchanged

I came across this command:

float example = 111.3547698;

((Math.Truncate(Example * 1000)) / 1000)

But I do not want to round. According to the command posted above, 111.3547698 -> 111.354

but I need it to stay: 111.3547

Are you going to be doing more math with the result, or just writing it somewhere? If the latter, there are much better ways. — Andrew, Mar 12 '15 at 21:11
No, I will not be doing any more math, just want to truncate to 4 places after the decimal and show it as the result. — SRT, Mar 12 '15 at 21:14
I tried adding another 0, but still the same answer and also it is rounding of to 3 digits. — SRT, Mar 12 '15 at 21:15
The problem is in how you are displaying it, show that code. — Scott Chamberlain, Mar 12 '15 at 21:29
hi, Scott, i did not understood, what you are asking me to show, could you please frame the question in a different way, please. — SRT, Mar 12 '15 at 21:42

score 4 · Answer 1 · edited Apr 13 '17 at 12:40

4

One way to force this sort of truncating is to subtract a small amount so that Math.Round works as desired.

Math.Round(111.3547698 - 0.00005, 4)

is equivalent to

Math.Round(111.3547198, 4)

which does give you the 111.3547 that you're looking for.

The general case would be

Math.Round(num - 0.5/(Math.Pow(10, digits)), digits)

Where digits > 0

See https://codereview.stackexchange.com/questions/51951/truncate-decimal-places for a similar question/answer.

edited Apr 13 '17 at 12:40

Community

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answered Mar 12 '15 at 21:12

Steve Desmond

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This works only for this case, but what is the value is different, this is just the example with a hard coded value, but if i want to truncate for different values, how do i do that? – SRT Mar 12 '15 at 21:43
added a general case to the solution above – Steve Desmond Mar 13 '15 at 00:29

score 0 · Answer 2 · edited May 23 '17 at 11:46

0

Your code don't even compile in last vertion of C#.

It says:

Literal of type double cannot be implicitly converted to type 'float'; use an 'F' suffix to create a literal of this type

That mean you should read about literals in C#

This peace of code that you probably copy from here have literal m that says to compiler this number will be decimal. If you want to work with float with same peace of code and truncate 4 digits you should use f literal and write like this:

float ex = 111.3547698f;
var ex4 = (Math.Truncate(ex * 10000f)) / 10000f;

edited May 23 '17 at 11:46

Community

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answered Mar 12 '15 at 21:27

teo van kot

12,350
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i tried with 10000f)) / 10000f, that is rounding off to three digits and giving the output as 111.355 – SRT Mar 12 '15 at 21:45
= ((Math.Truncate(XXXXXX.VALUE * 10000f)) / 10000f) -- 111.3547698 (Actual Value) ----- 111.355 (Return value) – SRT Mar 12 '15 at 21:52
XXXValue = ((Math.Truncate(xxxValueObj.VALUE * 10000f)) / 10000f). Where as i am trying to truncate the values which this XXXValue gives as output to 4 decimal places – SRT Mar 12 '15 at 22:05

Limiting float to 4 decimal places

2 Answers2