Thread: Floating point Hex.

I need to print a floating point number in hex using the IEE standards for a double.

I tried this but it didn't work:

Code:

double dNum=5.5;
printf("%X", dNum);

I also tried:

Code:

double dNum=5.5;
printf("%X", (int)dNum);

The second one just printed out the hex for an integer. I looked at the dNum in memory with the debuger and that is what I want. Is there anyway to just copy the exact hex number from memory without converting it back to decimal?

Is this what you want?

Code:

#include <stdio.h>
#include <string.h>

int main(void)
{
	int    i;
	double d = 5.5;
	unsigned char d_bytes[sizeof(d)];

	memcpy(d_bytes, &d, sizeof(d));

	for (i = 0; i < sizeof(d); i++)
	{
		printf("%02X", d_bytes[i]);
	}

	getchar();
}

It didn't work.
The result is supposed to be: 40B00000.

You had it backwords.

it goes like this:

Code:

for (i = sizeof(d)-1; i > 0; i--)
{
	printf("%02X", d_bytes[i]);
}

and the result is supposed to be: 4016000000000000 not 40B00000. It works now. Thanks for the help.

Code:

int		main( ) {
	#define FP_SZ	8
	
	union {
		double			fp;
		unsigned char	byte[ FP_SZ ];
	} x;
	
	int		i;
	
	x.fp = ( double ) 5.5;
	
	printf( "Floating Point: %f\n", x.fp );
	printf( "Hex: " );
	
	for ( i = 0; i < FP_SZ; ++i )
		printf( "%02X ", x.byte[ i ] );
	
	return 0;
}