59STL_bitset

基本概念

bitset对象的定义和初始化（用unsigned值初始化、用string对象初始化）

bitset对象上的操作

示例代码

#include <iostream>
#include <string>
#include <bitset>

using namespace std;

int main()
{
    bitset<32> a(156);   //a的大小是32位二进制，全部是0
    cout << a << endl;

    bitset<16> b(0xffff);   //赋值
    cout << b << endl;

    bitset<32> c(0xffff);
    cout << c << endl;

    bitset<32> d(156);      //十进制156会变成二进制
    cout << d << endl;

    string str("11111110000000111100001111");   //string初始化
    bitset<32> e(str, 5, 4);    //第五位开始，取4位数
    cout << e << endl;

    bitset<32> f(str, str.size()-5);    //string的最后五位用来初始化
    cout << f << endl;
    cout << endl;

    //any()和none()检查是否有1
    bool is_set = a.any();
    if(is_set)
        cout << "a里至少有一个1!" << endl;

    bool is_not_set = a.none(); //没有1
    if(is_not_set)
        cout << "a里没有一个1!" << endl;

    //count()统计1的个数
    size_t bits_set = a.count();
    cout << "a里一共有 " << bits_set << " 个1" << endl;

    cout << "a的大小；" << a.size() << endl;
    cout << "a里一共有 " << a.size() - bits_set << " 个0" << endl;
    cout << endl;

    bitset<32> x;
    cout << x << endl;

    x[5] = 1;           //使用下标修改值
    x.set(7);           //set把某一位置为1
    cout << x << endl;

    for(int index=0; index != 32; index += 2)
        x[index] = 1;
    cout << x << endl;

    x.set();            //全部置1
    cout << x << endl;

    x.reset();          //全部置0
    cout << x << endl;

    x.flip();           //取反操作
    cout << x << endl;

    unsigned long y = x.to_ulong();     //变成十进制数
    cout << y << endl;

    bitset<4> fourBits;
    cout << fourBits << endl;

    bitset<8> eightBits;
    cout << "请输入一个八位的二进制序列：";
    cin >> eightBits;
    cout << endl;

    cout << eightBits << endl;

    cout << "有 " << eightBits.count() << " 个1" << endl;
    cout << "有 " << eightBits.size() - eightBits.count() << " 个0" << endl;

    bitset<8> flipInput(eightBits);
    flipInput.flip();
    cout << flipInput << endl;

    bitset<8> eightMoreBits;
    cout << "请输入另外一个八位的二进制序列：";
    cin >> eightMoreBits;
    cout << endl;

    cout << (eightBits & eightMoreBits) << endl;  //位与，且优先级较低
    cout << (eightBits | eightMoreBits) << endl;  //位或
    cout << (eightBits ^ eightMoreBits) << endl;  //位亦或

    return 0;
}