C++ Unions bit fields task
- by learningtolive
Can somebody clear me out why would I use union and with what purpose the same address for the cin'ed variable and bit field (task from the Schildts C++ book)? In other words why would I use union for :
char ch;
struct byte bit;
// Display the ASCII code in binary for characters.
#include <iostream>
#include <conio.h>
using namespace std;
// a bit field that will be decoded
struct byte {
unsigned a : 1;
unsigned b : 1;
unsigned c : 1;
unsigned d : 1;
unsigned e : 1;
unsigned f : 1;
unsigned g : 1;
unsigned h : 1;
};
union bits {
char ch;
struct byte bit;
} ascii ;
void disp_bits(bits b);
int main()
{
do {
cin >> ascii.ch;
cout << ": ";
disp_bits(ascii);
} while(ascii.ch!='q'); // quit if q typed
return 0;
}
// Display the bit pattern for each character.
void disp_bits(bits b)
{
if(b.bit.h) cout << "1 ";
else cout << "0 ";
if(b.bit.g) cout << "1 ";
else cout << "0 ";
if(b.bit.f) cout << "1 ";
else cout << "0 ";
if(b.bit.e) cout << "1 ";
else cout << "0 ";
if(b.bit.d) cout << "1 ";
else cout << "0 ";
if(b.bit.c) cout << "1 ";
else cout << "0 ";
if(b.bit.b) cout << "1 ";
else cout << "0 ";
if(b.bit.a) cout << "1 ";
else cout << "0 ";
cout << "\n";
}
