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How to convert a double variable to binary data (bits)? Posted by reivaj7999 on 12 Aug 2005 at 8:32 AM

Hi everyone, how do you do?

I am having this problem, I do not know if it is possible, but I am trying to convert a double variable to binary data(bits).

I tried with the bitset container, but it seems that my compiler does not recognize the bitset.

Any ideas of how I can do this, of course if it is possible?

Thanks guys!
Regards Reivaj

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Re: How to convert a double variable to binary data (bits)? Posted by IDK on 12 Aug 2005 at 9:16 AM

: Hi everyone, how do you do?
:
: I am having this problem, I do not know if it is possible, but I am trying to convert a double variable to binary data(bits).
:
: I tried with the bitset container, but it seems that my compiler does not recognize the bitset.
:
: Any ideas of how I can do this, of course if it is possible?
:
: Thanks guys!
: Regards Reivaj
:
Floats are stored a little diferently in memmory than usual data...
Try to get the adress of where the double is stored and then make a byte
access it with the double's address.

Now make it binary.

Niklas Ulvinge aka IDK

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Re: How to convert a double variable to binary data (bits)? Posted by reivaj7999 on 12 Aug 2005 at 9:36 AM

This message was edited by reivaj7999 at 2005-8-12 9:49:24

: Floats are stored a little diferently in memmory than usual data...
: Try to get the adress of where the double is stored and then make a byte
: access it with the double's address.
:
: Now make it binary.
:
: Niklas Ulvinge aka IDK
Thank you Niklas,
But how can I accomplish this?
for instance I have this code...

double doubleValue = some_double_value;
// I get the address of doubleValue
double *doubleValueRef = &doubleValue;

...then, how can I make the access?
Regards Reivaj

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Re: How to convert a double variable to binary data (bits)? Posted by IDK on 12 Aug 2005 at 11:52 AM

This message was edited by IDK at 2005-8-12 11:55:9

This message was edited by IDK at 2005-8-12 11:54:22

: Thank you Niklas,
: But how can I accomplish this?
: for instance I have this code...
:

: double doubleValue = some_double_value;
: // I get the address of doubleValue
: double *doubleValueRef = &doubleValue;
:

: ...then, how can I make the access?
: Regards Reivaj
:
Like this:

double doubleValue = some_double_value;
byte *doubleAddress = &doubleValue;
//   at the red arrow ^ I want to get the address of doubleValue to doubleaddress
//make binary...
for(int i = 0; i<sizeof(double); i++) {
  for(int p = 7; p > 0; p++) {
    cout << (Math.Pow(2,p) & &doubleAddress)/Math.Pow(2,p);
  } //right at the red arrow ^ I want to get the value that's stored at the address doubleAddress.
  doubleAddress++;
}

This should be platform independent and you wont need any headers,
except math.h.
I'm not sure of how addresses are working in C/C++... That's why I wrote it in english first.

I hope you got how I've denscibed it here. I usually programming in
assembly and there it's all clear, but here I don't know...

Niklas Ulvinge aka IDK

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Re: How to convert a double variable to binary data (bits)? Posted by HK_MP5KPDW on 12 Aug 2005 at 10:29 AM

: Hi everyone, how do you do?
:
: I am having this problem, I do not know if it is possible, but I am trying to convert a double variable to binary data(bits).
:
: I tried with the bitset container, but it seems that my compiler does not recognize the bitset.
:
: Any ideas of how I can do this, of course if it is possible?
:
: Thanks guys!
: Regards Reivaj
:

What errors/warnings does your compiler report in regards to the bitset? The constructors for bitset don't accept a double as an argument so you have to be a bit creative when initializing a bitset with the contents of a double. If you had to use a bitset and assuming 8 byte doubles and 4 byte longs, I think this should work:

double dbl = 49958634.876359;
unsigned long* ulp = reinterpret_cast<unsigned long*>(&dbl);
bitset<64> bits1(*ulp);
bitset<64> bits2(*(++ulp));
bits2 <<= 32;    // Shift values left
bits2 |= bits1;  // Combine this part with other part
cout << bits2 << endl;

Which outputs on my machine:

0100000110000111110100100111011101010111000000101100100010000010

There may be some endian issues depending on your computer. Also, maybe somebody knows of an online converter to validate that.

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Re: How to convert a double variable to binary data (bits)? Posted by reivaj7999 on 12 Aug 2005 at 11:10 AM

: What errors/warnings does your compiler report in regards to the bitset? The constructors for bitset don't accept a double as an argument so you have to be a bit creative when initializing a bitset with the contents of a double. If you had to use a bitset and assuming 8 byte doubles and 4 byte longs, I think this should work:
:
:

double dbl = 49958634.876359;
: unsigned long* ulp = reinterpret_cast<unsigned long*>(&dbl);
: bitset<64> bits1(*ulp);
: bitset<64> bits2(*(++ulp));
: bits2 <<= 32;    // Shift values left
: bits2 |= bits1;  // Combine this part with other part
: cout << bits2 << endl;
:

:
: Which outputs on my machine:
:

0100000110000111110100100111011101010111000000101100100010000010

:
: There may be some endian issues depending on your computer. Also, maybe somebody knows of an online converter to validate that.
:
Thank you, I am working with Borland C++ 5.02 in a AMD AthlonXP 2600+ 2.09GHz and 1.0GB RAM, HD Freespace of 8.0GB, and I am having issues with bitset, here is my code...

#include<iostream>
#include<math>
#include<bitset>

void main()
{
	double value = M_PI;
   unsigned* valueRef = reinterpret_cast<unsigned*>(&value);

   bitset<64> lessSignificative(*valueRef);
   bitset<64> mostSignificative(*(++valueRef));

   mostSignificative <<= 32;
   mostSignificative |= lessSignificative;

   cout << mostSignificative << endl;
}

...and this are the compiler messages:
Info :Compiling C:\Trabajo\Servicio social\Servicio\test.cpp
Warn : string.h(549,3):Functions containing for are not expanded inline
Warn : string.h(557,3):Functions containing while are not expanded inline
Warn : string.h(563,3):Functions containing for are not expanded inline
Warn : string.h(575,3):Functions containing for are not expanded inline
Warn : string.cc(686,32):Comparing signed and unsigned values
Warn : BITSET.h(221,3):Functions containing for are not expanded inline
Warn : BITSET.h(267,3):Functions containing for are not expanded inline
Warn : BITSET.h(273,3):Functions containing for are not expanded inline
Warn : BITSET.h(279,3):Functions containing for are not expanded inline
Warn : BITSET.h(292,3):Functions containing for are not expanded inline
Warn : BITSET.h(305,3):Functions containing for are not expanded inline
Warn : BITSET.h(311,3):Functions containing for are not expanded inline
Warn : BITSET.h(340,3):Functions containing for are not expanded inline
Warn : BITSET.h(380,3):Functions containing for are not expanded inline
Warn : BITSET.h(399,3):Functions containing for are not expanded inline
Warn : BITSET.h(407,3):Functions containing for are not expanded inline
Warn : string.cc(658,2):Cannot create pre-compiled header: code in header
Error: test.cpp(10,11):Undefined symbol 'bitset'
Error: test.cpp(10,14):Ambiguous operators need parentheses
Error: test.cpp(10,33):Call to undefined function 'lessSignificative'
Error: test.cpp(11,14):Ambiguous operators need parentheses
Error: test.cpp(11,33):Call to undefined function 'mostSignificative'
Error: test.cpp(13,25):Illegal use of pointer
Error: test.cpp(14,24):Illegal use of pointer
Warn : test.cpp(17,2):'valueRef' is assigned a value that is never used
Is anything wrong with my code? Please Help!!!
Regards Reivaj

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Re: How to convert a double variable to binary data (bits)? Posted by HK_MP5KPDW on 12 Aug 2005 at 11:37 AM

: : What errors/warnings does your compiler report in regards to the bitset? The constructors for bitset don't accept a double as an argument so you have to be a bit creative when initializing a bitset with the contents of a double. If you had to use a bitset and assuming 8 byte doubles and 4 byte longs, I think this should work:
: :
: :

double dbl = 49958634.876359;
: : unsigned long* ulp = reinterpret_cast<unsigned long*>(&dbl);
: : bitset<64> bits1(*ulp);
: : bitset<64> bits2(*(++ulp));
: : bits2 <<= 32;    // Shift values left
: : bits2 |= bits1;  // Combine this part with other part
: : cout << bits2 << endl;
: :

: :
: : Which outputs on my machine:
: :

0100000110000111110100100111011101010111000000101100100010000010

: :
: : There may be some endian issues depending on your computer. Also, maybe somebody knows of an online converter to validate that.
: :
: Thank you, I am working with Borland C++ 5.02 in a AMD AthlonXP 2600+ 2.09GHz and 1.0GB RAM, HD Freespace of 8.0GB, and I am having issues with bitset, here is my code...
:

#include<iostream>
: #include<math>
: #include<bitset>
: 
: void main()
: {
: 	double value = M_PI;
:    unsigned* valueRef = reinterpret_cast<unsigned*>(&value);
: 
:    bitset<64> lessSignificative(*valueRef);
:    bitset<64> mostSignificative(*(++valueRef));
: 
:    mostSignificative <<= 32;
:    mostSignificative |= lessSignificative;
: 
:    cout << mostSignificative << endl;
: }

: ...and this are the compiler messages:
: Info :Compiling C:\Trabajo\Servicio social\Servicio\test.cpp
: Warn : string.h(549,3):Functions containing for are not expanded inline
: Warn : string.h(557,3):Functions containing while are not expanded inline
: Warn : string.h(563,3):Functions containing for are not expanded inline
: Warn : string.h(575,3):Functions containing for are not expanded inline
: Warn : string.cc(686,32):Comparing signed and unsigned values
: Warn : BITSET.h(221,3):Functions containing for are not expanded inline
: Warn : BITSET.h(267,3):Functions containing for are not expanded inline
: Warn : BITSET.h(273,3):Functions containing for are not expanded inline
: Warn : BITSET.h(279,3):Functions containing for are not expanded inline
: Warn : BITSET.h(292,3):Functions containing for are not expanded inline
: Warn : BITSET.h(305,3):Functions containing for are not expanded inline
: Warn : BITSET.h(311,3):Functions containing for are not expanded inline
: Warn : BITSET.h(340,3):Functions containing for are not expanded inline
: Warn : BITSET.h(380,3):Functions containing for are not expanded inline
: Warn : BITSET.h(399,3):Functions containing for are not expanded inline
: Warn : BITSET.h(407,3):Functions containing for are not expanded inline
: Warn : string.cc(658,2):Cannot create pre-compiled header: code in header
: Error: test.cpp(10,11):Undefined symbol 'bitset'
: Error: test.cpp(10,14):Ambiguous operators need parentheses
: Error: test.cpp(10,33):Call to undefined function 'lessSignificative'
: Error: test.cpp(11,14):Ambiguous operators need parentheses
: Error: test.cpp(11,33):Call to undefined function 'mostSignificative'
: Error: test.cpp(13,25):Illegal use of pointer
: Error: test.cpp(14,24):Illegal use of pointer
: Warn : test.cpp(17,2):'valueRef' is assigned a value that is never used
: Is anything wrong with my code? Please Help!!!
: Regards Reivaj
:

Yes, you've got some problems with the code you posted.

1. You probably need to put the following line after all of your #include statements.

using namespace std;

...or alternately change these lines:

bitset<64> lessSignificative(*valueRef);
bitset<64> mostSignificative(*(++valueRef));

to this:

std::bitset<64> lessSignificative(*valueRef);
std::bitset<64> mostSignificative(*(++valueRef));

2. main should always return an int.

3. This code has some issues:

unsigned* valueRef = reinterpret_cast<unsigned*>(&value);

Those both need to be unsigned long, just plain unsigned isn't going to work (unless your default unsigned int is 4 bytes, the same as an unsigned long?).

So, in total you should have this:

#include <iostream>
#include <math>
#include <bitset>
using namespace std;
 
int main()
{
    double value = M_PI;
    unsigned long* valueRef = reinterpret_cast<unsigned long*>(&value);
 
    bitset<64> lessSignificative(*valueRef);
    bitset<64> mostSignificative(*(++valueRef));
 
    mostSignificative <<= 32;
    mostSignificative |= lessSignificative;
 
    cout << mostSignificative << endl;

    return 0;
}

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