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C# Math.Round() on periodic doubles [duplicate]

I want to round my decimal value like 2.2222 to 2.23. When I use round,
decimal a = Math.Round((decimal)2.222, 2);
When I use ceiling, it cause 3
decimal c = Math.Ceiling((decimal)2.22);
How can I get 2.2222 to 2.23 ?

public static decimal CeilingAfterPoint(this decimal number, int digitsAfterPoint) {
return Math.Ceiling(number * (decimal)Math.Pow(10, digitsAfterPoint))
/ (decimal)Math.Pow(10, digitsAfterPoint);
}

Legacy question. But it deserves a right answer. Since .net core 3 you have been able to round decimals the following way:
Decimal.Round(2.222m, 2, MidpointRounding.ToPositiveInfinity);
It rounds upwards for the 2nd decimal.
MidpointRounding Docs

decimal c = Math.Ceiling((decimal)2.2222*100)/100;
but it's stupid.

try something like
decimal c = Math.Ceiling((decimal)2.222*100)/100;
but it fails if your value is 2.22

I solved my problem..
string n = "2.2222";
string[] s = n.Split('.');
if (s[1].Count() >= 3)
{
List<char> z = s[1].ToString().Take(2).ToList();
int c=Convert.ToInt32(z[0].ToString() + z[1].ToString()) + 1;
// int b = Convert.ToInt32(s[1].ElementAt(0).ToString() + s[1].ElementAt(1).ToString()) + 1;
string output= s[0] + "." + c.ToString();
}
now any number can put ,it will take 2 decimal value and add 1.Thanks.

Something is wrong with the accuracy of calculation between variables

I have some problems with my code where I think the accuracy is a bit off. I'll take out the declarations of variables from my code, so the code is as small as possible:
int a = Int32.Parse(tb_weight.Text);
double b = 0;
b = (a * 1.03) / 1000;
double g = 0;
g = (1.09 + (0.41 * (Math.Sqrt(50 / b))));
lbl_vertforce.Content = Math.Round((b * g * 9.81), 2);
So, tb_weight is a textbox where the input is made, and lets say the input is 5000, the label lbl_vertforce is showing 119,61 and according to my calculator, it should show 119,74. What is wroing here?

Doubles are not 100% precise and can vary in the least common digits. If you want exact precision you need to use Decimal type which has a bigger memory foot print, but was designed to be very precise. Unfortunately Math.Sqrt is not overloaded for Decimal and only works on doubles. I have provide code I found in another posting discussing the subject of Decimal Square roots: Performing Math operations on decimal datatype in C#?
public void YourCodeModifiedForDecimal()
{
int a = Int32.Parse(tb_weight.Text);
decimal b = 0;
b = (a* 1.03m) / 1000m;
decimal g = 0;
g = (1.09m + (0.41m * (Sqrt(50m / b))));
lbl_vertforce.Content = Math.Round((b* g * 9.81m), 2);
}
public static decimal Sqrt(decimal x, decimal? guess = null)
{
var ourGuess = guess.GetValueOrDefault(x / 2m);
var result = x / ourGuess;
var average = (ourGuess + result) / 2m;
if (average == ourGuess) // This checks for the maximum precision possible with a decimal.
return average;
else
return Sqrt(x, average);
}

You need to round g to 2 decimal places to get 119.74 in the final calculation.
g = Math.Round(1.09 + (0.41 * (Math.Sqrt(50 / b))), 2);

Printing numbers after decimal point

How can i print the numbers of a float/double variable after the decimal point?
For example for 435.5644 it will output 5644.

try with
fraction = value - (long) value;
or :
fraction = value - Math.Floor(value);

You can try the following:
double d = 435.5644;
int n = (int)d;
var v = d - n;
string s = string.Format("{0:#.0000}", v);
var result = s.Substring(1);
result: 5644

EDIT: reference to another question (http://stackoverflow.com/questions/4512306/get-decimal-part-of-a-number-in-javascript)
You can do the following:
double d = 435.5644;
float f = 435.5644f;
Console.WriteLine(Math.Round(d % 1, 4) * 10000);
Console.WriteLine(Math.Round(f % 1, 4) * 10000);
That will give you the integer part you looking for.
Best is to do it as Aghilas Yakoub answered, however, here below another option using string handling. Assuming all amounts will have decimals and that decimal separator is a dot (.) you just need to get the index 1.
double d = 435.5644;
Console.WriteLine(d.ToString().Split('.')[1]);
float f = 435.5644f;
Console.WriteLine(f.ToString().Split('.')[1]);
Otherwise you may get a Unhandled Exception: System.IndexOutOfRangeException.

Extremely basic division equation not working in c#

I can't get this to divide into a decimal. It is rounding to value 0.
private void button24_Click(object sender, EventArgs e)
{
double x = 0;
x = 1 / 2;
ans.Text = x.ToString();
}
When I debug, x is zero before it is sent to the textbox 'ans.'
I tried..and string variable is still zero..
double x = 1/5;
string displayX = x.ToString("0.0000");

It's integer division and those are the expected outputs.
double x = 1.0 / 5; // this will not perform integer division
double x = 1/5; // this does (1/5 = 0).
double x = 1D / 5; // this will not because 1 is treated as a double

You can do one of the follow:
double x = 1;
double y = 1.5;
double ans = x / y;

Replace double x = 1/5 with double x = 1.0/5 and that should fix it. Because both numbers you're dividing are integers, it still processes it as an integer, rather than as a double. When you think through logically, it makes some sense - it does the division in whatever form those numbers are and then saves it to the variable; the variable type is inconsequential to the actual equation.
(I realize there are other answers already, but hopefully this will help you see why the issue exists.)

Why do these division equations result in zero?

The result of all of the division equations in the below for loop is 0. How can I get it to give me a decimal e.g.:
297 / 315 = 0.30793650793650793650793650793651
Code:
using System;
namespace TestDivide
{
class Program
{
static void Main(string[] args)
{
for (int i = 0; i <= 100; i++)
{
decimal result = i / 100;
long result2 = i / 100;
double result3 = i / 100;
float result4 = i / 100;
Console.WriteLine("{0}/{1}={2} ({3},{4},{5}, {6})", i, 100, i / 100, result, result2, result3, result4);
}
Console.ReadLine();
}
}
}
Answer:
Thanks Jon and everyone, this is what I wanted to do:
using System;
namespace TestDivide
{
class Program
{
static void Main(string[] args)
{
int maximum = 300;
for (int i = 0; i <= maximum; i++)
{
float percentage = (i / (float)maximum) * 100f;
Console.WriteLine("on #{0}, {1:#}% finished.", i, percentage);
}
Console.ReadLine();
}
}
}

You're using int/int, which does everything in integer arithmetic even if you're assigning to a decimal/double/float variable.
Force one of the operands to be of the type you want to use for the arithmetic.
for (int i = 0; i <= 100; i++)
{
decimal result = i / 100m;
long result2 = i / 100;
double result3 = i / 100d;
float result4 = i / 100f;
Console.WriteLine("{0}/{1}={2} ({3},{4},{5}, {6})",
i, 100, i / 100d, result, result2, result3, result4);
}
Results:
0/100=0 (0,0,0, 0)
1/100=0.01 (0.01,0,0.01, 0.01)
2/100=0.02 (0.02,0,0.02, 0.02)
3/100=0.03 (0.03,0,0.03, 0.03)
4/100=0.04 (0.04,0,0.04, 0.04)
5/100=0.05 (0.05,0,0.05, 0.05)
(etc)
Note that that isn't showing the exact value represented by the float or the double - you can't represent 0.01 exactly as a float or double, for example. The string formatting is effectively rounding the result. See my article on .NET floating binary point for more information as well as a class which will let you see the exact value of a double.
I haven't bothered using 100L for result2 because the result would always be the same.

Try
i / 100.0

because i is an int: i / 100 performs integer division, then the result, that is always 0, is casted to the target type. You need to specify at least one non-int literal in your expression:
i / 100.0

Because i is an integer and 100 is an integer...so you have an integer division
Try (decimal)i / 100.0 instead

No matter where you store it, an integer divided by an integer will always be an integer.

You need to force a floating point operation "double / double" instead of an "int / int"
double result = (double)297 / (double)315 ;

this is integer division whatever the type of variable you storing in,
so int / int = int

double result3 = ((double)i) / 100;

Because i is a int value and you divide by an integer so the result is an integer ! and so you need to divide by 100.0 to have an implicit cast in float or specify 100f or 100d

In my case I had only vars and no int
float div = (var1 - var2) / float.Parse(var1.ToString());