Rounding a variable to two decimal places C# [duplicate]

问题

I am interested in how to round variables to two decimal places. In the example below, the bonus is usually a number with four decimal places. Is there any way to ensure the pay variable is always rounded to two decimal places?

  pay = 200 + bonus;
  Console.WriteLine(pay);

回答1:

Use Math.Round and specify the number of decimal places.

Math.Round(pay,2);

Math.Round Method (Double, Int32)

Rounds a double-precision floating-point value to a specified number of fractional digits.

Or Math.Round Method (Decimal, Int32)

Rounds a decimal value to a specified number of fractional digits.

回答2:

You should use a form of Math.Round. Be aware that Math.Round defaults to banker's rounding (rounding to the nearest even number) unless you specify a MidpointRounding value. If you don't want to use banker's rounding, you should use Math.Round(decimal d, int decimals, MidpointRounding mode), like so:

Math.Round(pay, 2, MidpointRounding.AwayFromZero); // .005 rounds up to 0.01
Math.Round(pay, 2, MidpointRounding.ToEven);       // .005 rounds to nearest even (0.00) 
Math.Round(pay, 2);    // Defaults to MidpointRounding.ToEven

(Why does .NET use banker's rounding?)

回答3:

decimal pay  = 1.994444M;

Math.Round(pay , 2);

回答4:

You can round the result and use string.Format to set the precision like this:

decimal pay = 200.5555m;
pay = Math.Round(pay + bonus, 2);
string payAsString = string.Format("{0:0.00}", pay);

回答5:

Make sure you provide a number, typically a double is used. Math.Round can take 1-3 arguments, the first argument is the variable you wish to round, the second is the number of decimal places and the third is the type of rounding.

double pay = 200 + bonus;
double pay = Math.Round(pay);
// Rounds to nearest even number, rounding 0.5 will round "down" to zero because zero is even
double pay = Math.Round(pay, 2, MidpointRounding.ToEven);
// Rounds up to nearest number
double pay = Math.Round(pay, 2, MidpointRounding.AwayFromZero);

回答6:

Pay attention on fact that Round rounds.

So (I don't know if it matters in your industry or not), but:

float a = 12.345f;
Math.Round(a,2);

//result:12,35, and NOT 12.34 !

To make it more precise for your case we can do something like this:

int aInt = (int)(a*100);
float aFloat= aInt /100.0f;
//result:12,34

回答7:

Use System.Math.Round to rounds a decimal value to a specified number of fractional digits.

var pay = 200 + bonus;
pay = System.Math.Round(pay, 2);
Console.WriteLine(pay);

MSDN References:

http://msdn.microsoft.com/en-us/library/system.math.round.aspx
http://msdn.microsoft.com/en-us/library/zy06z30k.aspx

回答8:

Console.WriteLine(decimal.Round(pay,2));

来源：https://stackoverflow.com/questions/12621640/rounding-a-variable-to-two-decimal-places-c-sharp

标签

variables

decimal

rounding