Double.NaN フィールド

定義

非数 (NaN) の値を表します。Represents a value that is not a number (NaN). このフィールドは定数です。This field is constant.

public: double NaN = NaN;
public const double NaN = NaN;
val mutable NaN : double
Public Const NaN As Double  = NaN

フィールド値

NaN の使用例を次に示します。The following example illustrates the use of NaN:

Double zero = 0;

// This condition will return false.
if ( (0 / zero) == Double::NaN )
{
   Console::WriteLine( "0 / 0 can be tested with Double::NaN." );
}
else
{
   Console::WriteLine( "0 / 0 cannot be tested with Double::NaN; use Double::IsNan() instead." );
}
Double zero = 0;
  
// This condition will return false.
if ((0 / zero) == Double.NaN) 
   Console.WriteLine("0 / 0 can be tested with Double.NaN.");
else 
   Console.WriteLine("0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.");
Dim zero As Double = 0

' This condition will return false.
If (0 / zero) = Double.NaN Then
    Console.WriteLine("0 / 0 can be tested with Double.NaN.")
Else
    Console.WriteLine("0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.")
End If

注釈

メソッドまたは演算子は、演算の結果が未定義の場合に NaN を返します。A method or operator returns NaN when the result of an operation is undefined. たとえば、次の例に示すように、0を0で除算した結果は NaNになります。For example, the result of dividing zero by zero is NaN, as the following example shows. (ただし、0以外の数値を0で除算すると、除数の符号に応じて PositiveInfinity または NegativeInfinityのいずれかが返されます)。(But note that dividing a non-zero number by zero returns either PositiveInfinity or NegativeInfinity, depending on the sign of the divisor.)

double zero = 0.0;
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero);
// The example displays the following output:
//         0 / 0 = NaN      
Dim zero As Double = 0
Console.WriteLine("{0} / {1} = {2}", zero, zero, zero/zero)
' The example displays the following output:
'         0 / 0 = NaN      

また、次の例に示すように、NaN 値を持つメソッド呼び出しまたは NaN 値に対する操作は NaNを返します。In addition, a method call with a NaN value or an operation on a NaN value returns NaN, as the following example shows.

double nan1 = Double.NaN;

Console.WriteLine("{0} + {1} = {2}", 3, nan1, 3 + nan1);
Console.WriteLine("Abs({0}) = {1}", nan1, Math.Abs(nan1));
// The example displays the following output:
//       3 + NaN = NaN
//       Abs(NaN) = NaN
Dim nan1 As Double = Double.NaN

Console.WriteLine("{0} + {1} = {2}", 3, nan1, 3 + nan1)
Console.WriteLine("Abs({0}) = {1}", nan1, Math.Abs(nan1))
' The example displays the following output:
'       3 + NaN = NaN
'       Abs(NaN) = NaN

値が数値でないかどうかを判断するには、IsNaN メソッドを使用します。Use the IsNaN method to determine whether a value is not a number. Equality 演算子は、2つの NaN 値が互いに等しくないと見なします。The Equality operator considers two NaN values to be unequal to one another. 一般に、Double 演算子を使用して Double.NaN を他の Double 値と比較することはできませんが、比較メソッド (EqualsCompareToなど) は使用できます。In general, Double operators cannot be used to compare Double.NaN with other Double values, although comparison methods (such as Equals and CompareTo) can. 次の例は、Double の比較演算子とメソッド間の動作の違いを示しています。The following example illustrates the difference in behavior between Double comparison operators and methods.

using System;

public class Example
{
   public static void Main()
   {
      Console.WriteLine("NaN == NaN: {0}", Double.NaN == Double.NaN); 
      Console.WriteLine("NaN != NaN: {0}", Double.NaN != Double.NaN); 
      Console.WriteLine("NaN.Equals(NaN): {0}", Double.NaN.Equals(Double.NaN)); 
      Console.WriteLine("! NaN.Equals(NaN): {0}", ! Double.NaN.Equals(Double.NaN)); 
      Console.WriteLine("IsNaN: {0}", Double.IsNaN(Double.NaN));

      Console.WriteLine("\nNaN > NaN: {0}", Double.NaN > Double.NaN); 
      Console.WriteLine("NaN >= NaN: {0}", Double.NaN >= Double.NaN); 
      Console.WriteLine("NaN < NaN: {0}", Double.NaN < Double.NaN);
      Console.WriteLine("NaN < 100.0: {0}", Double.NaN < 100.0); 
      Console.WriteLine("NaN <= 100.0: {0}", Double.NaN <= 100.0); 
      Console.WriteLine("NaN >= 100.0: {0}", Double.NaN > 100.0);
      Console.WriteLine("NaN.CompareTo(NaN): {0}", Double.NaN.CompareTo(Double.NaN)); 
      Console.WriteLine("NaN.CompareTo(100.0): {0}", Double.NaN.CompareTo(100.0)); 
      Console.WriteLine("(100.0).CompareTo(Double.NaN): {0}", (100.0).CompareTo(Double.NaN)); 
   }
}
// The example displays the following output:
//       NaN == NaN: False
//       NaN != NaN: True
//       NaN.Equals(NaN): True
//       ! NaN.Equals(NaN): False
//       IsNaN: True
//       
//       NaN > NaN: False
//       NaN >= NaN: False
//       NaN < NaN: False
//       NaN < 100.0: False
//       NaN <= 100.0: False
//       NaN >= 100.0: False
//       NaN.CompareTo(NaN): 0
//       NaN.CompareTo(100.0): -1
//       (100.0).CompareTo(Double.NaN): 1
Module Example
   Public Sub Main()
      Console.WriteLine("NaN = NaN: {0}", Double.NaN = Double.NaN) 
      Console.WriteLine("NaN <> NaN: {0}", Double.NaN <> Double.NaN) 
      Console.WriteLine("NaN.Equals(NaN): {0}", Double.NaN.Equals(Double.NaN)) 
      Console.WriteLine("Not NaN.Equals(NaN): {0}", Not Double.NaN.Equals(Double.NaN)) 
      Console.WriteLine("IsNaN: {0}", Double.IsNaN(Double.NaN))
      Console.WriteLine()
      Console.WriteLine("NaN > NaN: {0}", Double.NaN > 100.0) 
      Console.WriteLine("NaN >= NaN: {0}", Double.NaN >= 100.0) 
      Console.WriteLine("NaN < NaN: {0}", Double.NaN < Double.NaN)
      Console.WriteLine("NaN < 100.0: {0}", Double.NaN < 100.0) 
      Console.WriteLine("NaN <= 100.0: {0}", Double.NaN <= 100.0) 
      Console.WriteLine("NaN >= 100.0: {0}", Double.NaN > 100.0)
      Console.WriteLine("NaN.CompareTo(NaN): {0}", Double.NaN.CompareTo(Double.Nan)) 
      Console.WriteLine("NaN.CompareTo(100.0): {0}", Double.NaN.CompareTo(100.0)) 
      Console.WriteLine("(100.0).CompareTo(Double.NaN): {0}", (100.0).CompareTo(Double.NaN)) 
   End Sub
End Module
' The example displays the following output:
'       NaN == NaN: False
'       NaN != NaN: True
'       NaN.Equals(NaN): True
'       ! NaN.Equals(NaN): False
'       IsNaN: True
'
'       NaN > NaN: False
'       NaN >= NaN: False
'       NaN < NaN: False
'       NaN < 100.0: False
'       NaN <= 100.0: False
'       NaN >= 100.0: False
'       NaN.CompareTo(NaN): 0
'       NaN.CompareTo(100.0): -1
'       (100.0).CompareTo(Double.NaN): 1

適用対象

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