C# one number before floating point

Question

I need to somehow get one number before floating point and value after that floating point. Example:

Before: 212.12345;
After: 2.12345

Any Ideas?

I do not know the C# API, but how about converting the number to a String, then create a substring with the needed numbers and parse it to a double again? — Mirco, Jul 31 '13 at 06:38
you can convert it to string and than use substring method combined by indexOf method. — Habibillah, Jul 31 '13 at 06:39

score 8 · Answer 1 · edited May 23 '17 at 12:20

8

Assuming you have:

decimal x = 212.12345m;

you can use the modulo operator:

decimal result = x % 10;

Note that the number should be represented as a decimal if you care about the accurate value.

edited May 23 '17 at 12:20

Community

answered Jul 31 '13 at 06:42

Kobi

4

Although if the exact decimal digits are important, the OP should consider using `decimal` rather than `double`. – Jon Skeet Jul 31 '13 at 06:43
@JonSkeet - Good point! the question mentions floating point, I'm not sure what that means for the OP. Either way, `%` should work. – Kobi Jul 31 '13 at 06:46
He is removing two digits 12 before decimal point as 212.12345 need to be 2.12345, How modulus operator would do that? – Adil Jul 31 '13 at 06:51
@Adil - The assumption here is `1234.5` -> `4.5`, not `1.5`. This is marked by the OP using bold text: "21 **2.12345**", though I agree the question is very poorly written. – Kobi Jul 31 '13 at 06:53
I misunderstood that. – Adil Jul 31 '13 at 06:55
He needs to write a parser to chop off the numbers 2 places before the ".". – ZeroPhase Jul 31 '13 at 07:00
@ZeroPhase - Isn't that another *assumption*? We don't *know* whether the OP has a string or a numeric value. Either way, if the OP is doing an arithmetic operation, they can parse the string - if this is a number, you don't need to parse it. If this is a string, you can easily search for `.` and take a substring. – Kobi Jul 31 '13 at 07:03

Tomer W · Answer 2 · 2013-07-31T12:27:29.330

0

my approach was to find the number 210, and substract it....
will work for any number as well as smaller then 10.

double f1 = 233.1234;
double f2 = f1 - (((int)f1 / 10) * 10);

edited Jul 31 '13 at 12:27

answered Jul 31 '13 at 06:43

Tomer W

1

Have you tried your code? This will output `2.125`. Float is not very precise. If you will change to double, you also will not get precise result: `2.12345000001369`. – Sergey Berezovskiy Jul 31 '13 at 06:57
@lazyberezovsky you are right, float isn't too percise, double is better, but is there a way to overcome floating point inacuracies? – Tomer W Jul 31 '13 at 12:30
Yes, there is a way - use `decimal` type – Sergey Berezovskiy Jul 31 '13 at 12:38

score 0 · Answer 3 · edited Jul 31 '13 at 06:52

0

try this

double x = 1; 
var y = x/10; 
var z = (y % (Math.Floor(y))) * 10;

edited Jul 31 '13 at 06:52

Soner Gönül

answered Jul 31 '13 at 06:45

Rex

score 0 · Answer 4 · answered Jul 31 '13 at 06:45

0

You can do like this:

public double GetFirst(double a)
{
    double b = a / 10.0;
    return (b - (int)b) * 10.0;
}

answered Jul 31 '13 at 06:45

score 0 · Answer 5 · edited Jul 31 '13 at 06:52

0

Try this code

string num = "15464612.12345";
string t = num.Split('.')[0];
num = t[t.Length-1].ToString() + "." + num.Split('.')[1];

edited Jul 31 '13 at 06:52

Soner Gönül

answered Jul 31 '13 at 06:47

Sandip

wont work in many situations like: `num = 123845` or `regional settings set numbers to exponent representation 1.546461212345e7` or alternativly `regional use comma instead of dot like 15464612,12345` – Tomer W Jul 31 '13 at 13:28

5 Answers5