Subj : Re: Any help on why?
To   : borland.public.cpp.borlandcpp
From : Bob Gonder
Date : Wed Jul 07 2004 10:32 am

Thomas Maeder [TeamB] wrote:

>What does "The Hex representation of a floating point number" mean?
>What is result of applying that representation to 3.1415?

Dunno as I dislike the inaccuracy of floats and doubles, and I've
never had enough desire to learn *exactly* how the mantisa/etc are
encoded.  However, the Hex of it shows the full implementation. Now
I've forgotten what the value portion is.... I remember the mantisa
scales the result so there are no leading zeros, but I forget what the
"number" portion is called......

OP showed output that looks a lot like the interal of a float to me:
>Given arguments: 1.5, 2.5, 3.5 and 4.5
>The number of arguments is : 4
>0  0, 3FF80000
>1  0, 40040000
>2  0, 400C0000
>3  0, 40120000

Ok, I'll write a proggie.
BCB5.
pi pushes 8 bytes

	{char	pie[40];
	float pi = 3.1415;
	int	i;
	for( i=0;i<10;i++)
	{	sprintf(pie,"pi=%f %LX",pi,pi);
		cputs( pie);
		cputs("\n\r");//works better on my console than \r\n
		pi+=pi;
	}

pi=3.141500	 400921CAC0000000
pi=6.283000	 401921CAC0000000
pi=12.566000	 402921CAC0000000
pi=25.132000	 403921CAC0000000
pi=50.264000	 404921CAC0000000
pi=100.528000	 405921CAC0000000
pi=201.056000	 406921CAC0000000
pi=402.112000	 407921CAC0000000
pi=804.223999	 408921CAC0000000
pi=1608.447998	 409921CAC0000000

Looks like 400 is the mantisa and 31415 == 921cac

.