[笔记] 整理bitset的常用方法

参考链接

• cpp reference bitset
• cpp reference bitset头文件

类模板 bitset 表示一个 N 位的固定大小序列。

初始化一个bitset

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

using std::string;
using std::bitset;
using std::cout;
using std::endl;


int main()
{

    bitset<10> myBit;   //定义一个默认的bitset对象，大小为10，值为默认值
    bitset<10> myBit2 = 0b0110110111;   //通过二进制数初始化一个bitset对象
    bitset<10> myBit3 = 439;   //通过整数值初始化bitset对象，和myBit2相同
    bitset<10> myBit4(string("1101110010"));   //通过字符串表示二进制数初始化bitset对象
    string bitStr = "ABAABABABBBA";
    bitset<10> myBit5(bitStr, 0, std::string::npos, 'A', 'B');  //使用字符初始化，并指定代替0和1的字符，A是0,B是1

    return 0;
}

使用[]访问bitset的某一位元素

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


using std::string;
using std::bitset;
using std::cout;
using std::endl;


int main()
{

    bitset<10> myBit;   //定义一个默认的bitset对象，大小为10，值为默认值
    bitset<10> myBit2 = 0b0110110111;   //通过二进制数初始化一个bitset对象
    bitset<10> myBit3 = 439;   //通过整数值初始化bitset对象，和myBit2相同
    bitset<10> myBit4(string("1101110010"));   //通过字符串表示二进制数初始化bitset对象
    string bitStr = "ABAABABABB";
    bitset<10> myBit5(bitStr, 0, std::string::npos, 'A', 'B');  //使用字符初始化，并指定代替0和1的字符，A是0,B是1

    cout << "value of myBit:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit[idx];     //0
    }
    cout << endl;

    cout << "value of myBit2:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit2[idx];     //0
    }
    cout << endl;

    cout << "value of myBit3:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit3[idx];     //0
    }
    cout << endl;


    cout << "value of myBit4:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit4[idx];     //0
    }
    cout << endl;



    cout << "value of myBit5:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit5[idx];     //0
    }
    cout << endl;
    return 0;
}

运行结果：

value of myBit:0000000000
value of myBit2:1110110110
value of myBit3:1110110110
value of myBit4:0100111011
value of myBit5:1101010010

修改元素的方式

• set(idx):将idx位设置为1
• set(idx, val)：将idx位设置为val的值，1/0
• reset(idx)：将idx位设置为0
• flip()：将所有的位的值翻转

其他访问元素的方式

• test(idx):返回idx位对应的值1/0
• all():测试是否是所有位都被设置位1
• any():测试是否有任意一位被设置为1
• none():测试所有位都没有被设置为1,即所有位都是0

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


using std::string;
using std::bitset;
using std::cout;
using std::endl;


int main()
{

    bitset<10> myBit;   //定义一个默认的bitset对象，大小为10，值为默认值

    cout << "test value of myBit:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit.test(idx);     //0
    }
    cout << endl;

    myBit.set(3);   //只有index 3的位置是1
    cout << "set 3:" << myBit.test(3) << endl;
    cout << "all:" << myBit.all() << " any:" << myBit.any() << " none:" << myBit.none() << endl;
    myBit.reset(3); //index 3的值被设定位0
    cout << "reset 3:" << myBit.test(3) << endl;
    cout << "all:" << myBit.all() << " any:" << myBit.any() << " none:" << myBit.none() << endl;
    myBit.flip(); //所有的值都是1

    cout << "After flip test value of myBit:";
    for(uint8_t idx = 0; idx < 10; idx++)
    {
        cout << myBit.test(idx);
    }
    cout << endl;
    cout << "all:" << myBit.all() << " any:" << myBit.any() << " none:" << myBit.none() << endl;

    return 0;
}

输出结果

test value of myBit:0000000000
set 3:1
all:0 any:1 none:0
reset 3:0
all:0 any:0 none:1
After flip test value of myBit:1111111111
all:1 any:1 none:0