Thread: Bitwise operations on unsigned character

A few months ago, I picked up a very useful function for outputting a binary string onto the screen.

Code:

void bits_uint(int value)
{
   int bit;
   for ( bit = (~0U >> 1) + 1; bit > 0; bit >>= 1 )
   {
      cout << (value & bit ? '1' : '0');
   }
   cout << endl;
}

This time, I wanted to make it a template function because I thought it would be neat, and because I wouldn't have to define a different function for each argument type:

Code:

template<class T>
void bits_uint(T value)
{
   T bit;
   for ( bit = /* msb */(~0 >> 1) + 1; bit > 0; bit >>= 1 )
   {
      cout << (value & bit ? '1' : '0');
   }
   cout << endl;
}

When I tried implementing the function as one of type

Code:

bit_uint<unsigned char>(whatever)

it did nothing because the bit was assigned a 0. My guess is, this happens because Intel CPUs are little endian, and the most significant bit is actually the 32nd and not the 8th as one would expect in a character.
Would there be a way to create a function which could print the binary string for any native type in c++? For example, float, double, char, etc.?

Thanks. Guess I won't have to implement my unruly function anymore.

BTW, I got my function to work. Seems I should have split the assignment into separate lines. Working with integers on the right side and an unsigned character on the left would have simply assigned an integer to the l-value. How stupid of me.

Code:

template<class T>
void bits_uint(T value)
{
   T bit = ~0;
   bit >>= 1;
   bit++;
   for ( ; bit > 0; bit >>= 1 )
   {
      cout << (value & bit ? '1' : '0');
   }
   cout << endl;
}

I needed to know the interior workings of a class I was making.

I had some private integer variables defined in bitfields. Then, I wanted to use bitwise operations to compare two classes.

For the curious, here's my class:

Code:

class Phoneme{
private:
	UINT alveolar		:1;
	UINT bilabial		:1;
	UINT continuant		:1;
	UINT glottal		:1;
	UINT labiodental	:1;
	UINT lateral		:1;
	UINT nasal			:1;
	UINT plosive		:1;
	UINT tap			:1;
	UINT trill			:1;
	UINT velar			:1;
	UINT voiced			:1;
	UINT vocalic		:1;	
public:
	Phoneme(){}
	~Phoneme(){}
	void set_bilabial(int i = 1){bilabial = i;}
	void set_continuant(int i = 1){continuant = i;}
	void set_glottal(int i = 1){glottal = i;}
	void set_labiodental(int i = 1){labiodental = i;}
	void set_lateral(int i = 1){lateral = i;}
	void set_nasal(int i = 1){nasal = i;}
	void set_plosive(int i = 1){plosive = i;}
	void set_tap(int i = 1){tap = i;}
	void set_trill(int i = 1){trill = i;}
	void set_velar(int i = 1){velar = i;}
	void set_vocalic(int i = 1){vocalic = i;}	
	void set_voiced(int i = 1){voiced = i;}
	virtual void initialize(){bilabial = continuant = glottal = labiodental = lateral =
		nasal = plosive = tap = trill = velar = vocalic = voiced = 0;}
	friend operator-(Phoneme& p1, Phoneme& p2);
};

Still in the working stages.

One question about the bitset class or function or whatever it is.

I tried the following code but it gave me an error message:

Code:

Phoneme b;
... //initialize this and that
cout << bitset<MAX_BITS>(*(unsigned int*)(&b)) << endl;

but the following does:

Code:

cout << bitset<MAX_BITS>((*(unsigned int*)(&b))) << endl;

Why does giving it an extra set of parentheses make it work? I mean, wouldn't the dereference operator have precedence over whatever it was bitset was doing?