write binary representation to output

[wongjoekmeu@yahoo.com]

Dear all,
I was wondering how in C++ the code would look like if I want to write
the binary notation of a unsigned char to standard output or any other
basic data type, like int, unsigned int, float and so forth.
Thanks in advance.
RR

[Juha Nieminen]

Re: write binary representation to output

wongjoekmeu@yah oo.com wrote:

I was wondering how in C++ the code would look like if I want to write
the binary notation of a unsigned char to standard output or any other
basic data type, like int, unsigned int, float and so forth.

#include <iostream>
#include <climits>

template<typena me Type>
void printBinaryRepr esentation(cons t Type& value)
{
// Resolve if this is a big-endian or a little-endian system:
int dummy = 1;
bool littleEndian = (*reinterpret_c ast<char*>(&dum my) == 1);

// The trick is to create a char pointer to the value:
const unsigned char* bytePtr =
reinterpret_cas t<const unsigned char*>(&value);

// Loop over the bytes in the value:
for(unsigned i = 0; i < sizeof(Type); ++i)
{
unsigned char byte;
if(littleEndian ) // we have to traverse the value backwards:
byte = bytePtr[sizeof(Type) - i - 1];
else // we have to traverse it forwards:
byte = bytePtr[i];

// Print the bits in the byte:
for(int bitIndex = CHAR_BIT-1; bitIndex >= 0; --bitIndex)
{
std::cout << ((byte >bitIndex) & 1);
}
}

std::cout << std::endl;
}

[Alf P. Steinbach]

Re: write binary representation to output

* wongjoekmeu@yah oo.com:

>
I was wondering how in C++ the code would look like if I want to write
the binary notation of a unsigned char to standard output or any other
basic data type, like int, unsigned int, float and so forth.

E.g.

<code>
#include <iostream // std::cout, std::ostream
#include <ostream // operator<<, std::endl
#include <bitset // std::bits
#include <climits // CHAR_BIT

static unsigned const bitsPerByte = CHAR_BIT;

template< typename T >
struct BitSize
{
enum { value = bitsPerByte*siz eof( T ) };
};

template< typename T >
std::bitset< BitSize<T>::val ue bitsetFrom( T const& v )
{
typedef std::bitset< BitSize<T>::val ue BitSet;

BitSet result;
unsigned char const* p = reinterpret_cas t<unsigned char const*>( & v );

// Uses little-endian convention for bit numbering.
for( size_t i = sizeof(T)-1; i != size_t(-1); --i )
{
result <<= bitsPerByte;
result |= BitSet( p[i] );
}
return result;
}

int main()
{
using namespace std;

int const i = 1234;
float const f = 1234.567;

cout << bitsetFrom( i ) << endl;
cout << bitsetFrom( f ) << endl;
}
</code>


Cheers, & hth,.

- Alf

[James Kanze]

Re: write binary representation to output

On 19 avr, 10:19, Juha Nieminen <nos...@thanks. invalidwrote:

wongjoek...@yah oo.com wrote:

I was wondering how in C++ the code would look like if I
want to write the binary notation of a unsigned char to
standard output or any other basic data type, like int,
unsigned int, float and so forth.

#include <iostream>
#include <climits>

template<typena me Type>
void printBinaryRepr esentation(cons t Type& value)
{
// Resolve if this is a big-endian or a little-endian system:
int dummy = 1;
bool littleEndian = (*reinterpret_c ast<char*>(&dum my) == 1);

And what about middle endian? If a type has more than two
bytes, then more than two orders are possible, and in fact, I've
seen at least three for long (on very common machines, no less).

For the rest, I don't think that this is what he was looking
for, and even if it was, I don't see any reason to access byte
by byte.

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

[Juha Nieminen]

Re: write binary representation to output

James Kanze wrote:

And what about middle endian?

Most probably we can ignore obscure architectures.

For the rest, I don't think that this is what he was looking
for, and even if it was, I don't see any reason to access byte
by byte.

How else? The size of the type will be n bytes, so accessing byte by
byte is the most logical choice. How else would you do it?

[Charles Coldwell]

Re: write binary representation to output

"wongjoekmeu@ya hoo.com" <wongjoekmeu@ya hoo.comwrites:

Dear all,
I was wondering how in C++ the code would look like if I want to write
the binary notation of a unsigned char to standard output or any other
basic data type, like int, unsigned int, float and so forth.
Thanks in advance.
RR

How about this:

#include <iostream>
#include <iomanip>

template<typena me Tstruct binary_traits
{
typedef T int_t;
};

template<struct binary_traits<f loat>
{
typedef int int_t;
};

template<struct binary_traits<d ouble>
{
typedef long long int_t;
};

template<typena me T>
void output(T x)
{
std::cout << std::setw(sizeo f(x)*2) << std::setfill('0 ') << std::hex
<< * reinterpret_cas t<typename binary_traits<T >::int_t *>(&x)
<< std::endl;
}

int main(int argc, char *argv[])
{
output(10);
output(10L);
output(10LL);
output(0.1f);
output(0.1);

return 0;
}



--
Charles M. "Chip" Coldwell
"Turn on, log in, tune out"
GPG Key ID: 852E052F
GPG Key Fingerprint: 77E5 2B51 4907 F08A 7E92 DE80 AFA9 9A8F 852E 052F

[James Kanze]

Re: write binary representation to output

On 20 avr, 11:41, Juha Nieminen <nos...@thanks. invalidwrote:

James Kanze wrote:

And what about middle endian?

Most probably we can ignore obscure architectures.

That was a Microsoft compiler, on an Intel architecture. I
don't know that the word "obscure" is appropriate in such cases.

For the rest, I don't think that this is what he was looking
for, and even if it was, I don't see any reason to access byte
by byte.

How else? The size of the type will be n bytes, so accessing
byte by byte is the most logical choice. How else would you do
it?

As itself?

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientier ter Datenverarbeitu ng
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

[Juha Nieminen]

Re: write binary representation to output

James Kanze wrote:

>>For the rest, I don't think that this is what he was looking
>>for, and even if it was, I don't see any reason to access byte
>>by byte.

>

>How else? The size of the type will be n bytes, so accessing
>byte by byte is the most logical choice. How else would you do
>it?

>
As itself?

How do you access individual bits of a double? (Or a struct containing
several member variables, for example.)