When you selected NaN for int, why does the value change depending on whether it is assigned to a variable or not?

Question

Bringing double.NaN to int will be 0.

Console.WriteLine(unchecked((int)double.NaN));    // 0

However, assigning the variable double.NaN to a variable, and then casting to int will be -2147483648.

double value = double.NaN;
Console.WriteLine (unchecked ((int) value));    // -2147483648
Console.WriteLine ((int) value);                // -2147483648

Why does the result change depending on whether to assign it to a variable or not?

C # specification

6.2.1 Explicit numerical conversions

• In the tested context, the conversion is as follows:
  • If the operand value is NaN or infinite, a System.OverflowException is thrown.
  • Otherwise, the source operand is rounded to zero to the nearest integer value. If this integer value is within the destination range, then this value is the result of the conversion.
  • System.OverflowException.
• .
  • NaN , .
  • . , .
  • .

Envrionment

• : Visual Studio 2013
• Rimtime:.NET Framework 4.6.0
• : Windows 10 Version 1607
• : Intel Core i7 920

:

Console.WriteLine(Environment.OSVersion);    // Microsoft Windows NT 6.2.9200.0
Console.WriteLine(Environment.Version);      // 4.0.30319.42000

Answer 1

unchecked. Thatswhy , , unchecked.

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( ).

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, , -2147483648 . .

Answer 2

, , , . 0, NaN. int, Int32 , double. , , :

• NaN , . .
• , .

int, "-2147483648", , 32- . , NaN double.NegativeInfinity . double.NegativeInfinity int.MinValue, , .

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