How do I display the binary representation of a float or double?

Question

I'd like to display the binary (or hexadecimal) representation of a floating point number. I know how to convert by hand (using the method here), but I'm interested in seeing code samples that do the same.

Although I'm particularly interested in the C++ and Java solutions, I wonder if any languages make it particularly easy so I'm making this language agnostic. I'd love to see some solutions in other languages.

EDIT: I've gotten good coverage of C, C++, C#, and Java. Are there any alternative-language gurus out there who want to add to the list?

Answer 1

C/C++ is easy.

union ufloat {   float f;   unsigned u; };  ufloat u1; u1.f = 0.3f; 

Then you just output u1.u. You can adapt this implementation.

Doubles just as easy.

union udouble {   double d;   unsigned long u; } 

because doubles are 64 bit.

Java is a bit easier: use Float.floatToRawIntBits() combined with Integer.toBinaryString() and Double.doubleToRawLongBits combined with Long.toBinaryString().

Answer 2

In C:

int fl = *(int*)&floatVar; 

&floatVar would get the adress memory then (int*) would be a pointer to this adress memory, finally the * to get the value of the 4 bytes float in int. Then you can printf the binary format or hex format.