bitwise.cpp

Think in C++ 第二版源码

//: C03:Bitwise.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Demonstration of bit manipulation
#include <iostream>
using namespace std;

// Display a byte in binary:
void printBinary(const unsigned char val) {
  for(int i = 7; i >= 0; i--)
    if(val & (1 << i))
      cout << "1";
    else
      cout << "0";
}

// A macro to save typing:
#define PR(STR, EXPR) \
  cout << STR; printBinary(EXPR); cout << endl;  

int main() {
  unsigned int getval;
  unsigned char a, b;
  cout << "Enter a number between 0 and 255: ";
  cin >> getval; a = getval;
  PR("a in binary: ", a);
  cout << "Enter a number between 0 and 255: ";
  cin >> getval; b = getval;
  PR("b in binary: ", b);
  PR("a | b = ", a | b);
  PR("a & b = ", a & b);
  PR("a ^ b = ", a ^ b);
  PR("~a = ", ~a);
  PR("~b = ", ~b);
  // An interesting bit pattern:
  unsigned char c = 0x5A; 
  PR("c in binary: ", c);
  a |= c;
  PR("a |= c; a = ", a);
  b &= c;
  PR("b &= c; b = ", b);
  b ^= a;
  PR("b ^= a; b = ", b);
} ///:~