Double.Nan值
此常數的值是零被零除所得到的結果。
當運算結果未定義時返回此常數。
使用 IsNaN 確定值是否爲非數字。不可能通過將某個值與另一個等於 NaN 的值進行比較來確定該值是否不是數字。
下面的代碼示例演示如何使用 NaN:
Visual Basic
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
C#
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.");
}
C++
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." );
}
J#
Double zero = new Double(0);
// This condition will return false.
if (0 / zero.doubleValue() == 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.");
}
以上都會輸出
0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.
當運算結果未定義時返回此常數。
使用 IsNaN 確定值是否爲非數字。不可能通過將某個值與另一個等於 NaN 的值進行比較來確定該值是否不是數字。
下面的代碼示例演示如何使用 NaN:
Visual Basic
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
C#
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.");
}
C++
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." );
}
J#
Double zero = new Double(0);
// This condition will return false.
if (0 / zero.doubleValue() == 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.");
}
以上都會輸出
0 / 0 cannot be tested with Double.NaN; use Double.IsNan() instead.
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