3.1.2　二元算术运算符（浮点类型的特殊性）

decimal decimalNumber = 4.2M;
double doubleNumber1 = 0.1F * 42F;
double doubleNumber2 = 0.1D * 42D;
float floatNumber = 0.1F * 42F;

Trace.Assert(decimalNumber != (decimal)doubleNumber1);
// Displays: 4.2 != 4.20000006258488
System.Console.WriteLine(
"{0} != {1}", decimalNumber, (decimal)doubleNumber1);

Trace.Assert((double)decimalNumber != doubleNumber1);
// Displays: 4.2 != 4.20000006258488
System.Console.WriteLine(
"{0} != {1}", (double)decimalNumber, doubleNumber1);

Trace.Assert((float)decimalNumber != floatNumber);
// Displays: (float)4.2M != 4.2F
System.Console.WriteLine(
"(float){0}M != {1}F",
(float)decimalNumber, floatNumber);

Trace.Assert(doubleNumber1 != (double)floatNumber);
// Displays: 4.20000006258488 != 4.20000028610229
System.Console.WriteLine(
"{0} != {1}", doubleNumber1, (double)floatNumber);

Trace.Assert(doubleNumber1 != doubleNumber2);
// Displays: 4.20000006258488 != 4.2
System.Console.WriteLine(
"{0} != {1}", doubleNumber1, doubleNumber2);

Trace.Assert(floatNumber != doubleNumber2);
// Displays: 4.2F != 4.2D
System.Console.WriteLine(
"{0}F != {1}D", floatNumber, doubleNumber2);

Trace.Assert((double)4.2F != 4.2D);
// Display: 4.19999980926514 != 4.2
System.Console.WriteLine(
"{0} != {1}", (double)4.2F, 4.2D);

Trace.Assert(4.2F != 4.2D);
// Display: 4.2F != 4.2D
System.Console.WriteLine(
"{0}F != {1}D", 4.2F, 4.2D);

4.2 != 4.20000006258488
4.2 != 4.20000006258488
(float)4.2M != 4.2F
4.20000006258488 != 4.20000028610229
4.20000006258488 != 4.2
4.2F != 4.2D
4.19999980926514 != 4.2
4.2F != 4.2D 

float n=0f;
// Displays: Nan
System.Console.WriteLine(n / 0);

 // Displays: -Infinity
System.Console.WriteLine(-1f / 0);
// Displays: Infinity
System.Console.WriteLine(3.402823E+38f * 2f);    

负无穷大
正无穷大