C++位运算

本文代码主要是对《程序员面试宝典(第四版)》中第12章位运算与嵌入式编程章节的位运算进行学习，实验检测了自己的理解。

#include <iostream>
#include <stdio.h>

using namespace std;

// 1
struct a
{
  int x : 1;
  int y : 2;
  int z : 3;
};

//2
#define BIT_MASK(bit_pos) (0x01<<(bit_pos))
int Bit_Reset(unsigned int *val, unsigned char pos)
{
  if (pos >= sizeof(unsigned int) * 8)
  {
    return 0;
  }
  *val = (*val & ~BIT_MASK(pos));
  return 1;
}

//3
#define MAX 255
typedef short Int16;
struct B
{
public:
  int m_iNum;
};

int main()
{
  //位制转换
  cout << "****位制转换****" << endl;
  printf("%f \n", 5);
  printf("%f \n", 5.01);

  printf("%d \n", 5.01);
  printf("%d \n", 5);

  cout << 5 << endl;
  cout << 5.01 << endl;
  cout << endl;

  cout << "****结构体位制****" << endl;
  a d;
  cout << "&d = " << &d << endl;
  d.z = d.x + d.y;
  cout << "d.x = " << d.x << endl;
  cout << "d.y = " << d.y << endl;
  cout << "d.z = " << d.z << endl;
  cout << "sizeof(d) = " << sizeof(d) << endl;
  cout << endl;

  cout << "****比特位掩膜****" << endl;
  unsigned int x = 0xffffffff;
  unsigned char y = 4;
  Bit_Reset(&x, y);
  cout << /*hex <<*/ x << endl;
  cout << endl;

  cout << "****const_cast****" << endl;
  B b0;
  b0.m_iNum = 100;
  const B b1 = b0;
  //b1.m_iNum = 100;  // error !
  cout << "b0.m_iNum = " << b0.m_iNum << " " << "b1.m_iNum = " << b1.m_iNum << endl;
  const_cast<B&>(b1).m_iNum = 200; // const_cast去掉b1的const属性，并重新赋值200
  cout << "b0.m_iNum = " << b0.m_iNum << " " << "b1.m_iNum = " << b1.m_iNum << endl;
  cout << endl;

  return 0;
}