question on float type

How can I detect an value is 4 bytes float type 开发者_JS百科or 8 byte float type or not both in C#?

if (obj.GetType() == typeof(float))
    // 4-byte float
else if (obj.GetType() == typeof(double))
    // 8-byte float
else
    // other

Alternatively, this should do the same thing:

if (obj is float)
    // 4-byte float
else if (obj is double)
    // 8-byte float
else
    // other

float in C# is always an alias for System.Single, which is always a 4 byte floating point value.

double in C# is always an alias for System.Double, which is an 8 byte floating point value.

If you are dealing with a float value, in C#, it is always 4 bytes. This is not platform dependent, but rather guaranteed by the C# specification.

The C# spec, section 1.3 (Types and variables) states this explicitly:

The two floating point types, float and double, are represented using the 32-bit single-precision and 64-bit double-precision IEEE 754 formats.

To see it your variable is a float or not, use the following code

if( myVariable is float ){
  ...
}

To see the actual size of float if that is what you need:

int length = sizeof(float);

You cannot use sizeof(myVariable), so you have to use both of the two approaches above.