c++ 位类型 bitset

c++ 位类型 bitset

头文件

详细说明：http://www.cplusplus.com/reference/bitset/bitset/

使用心得总结：

可以非常方便的去取int或long，或longlong的每一位的bit

可以方便的进行二进制字符串到ulong，ullong的转换

容易将一个字符的ascll码转成bit的表示

#include <string>
#include <iostream>
#include <string.h>
#include <bitset>

using namespace std;

int main()
{
    cout<<"a"<<endl;
    bitset<8> a("00000011");
    cout<<a.count()<<endl;
    cout<<a.to_ulong()<<endl;
    cout<<sizeof(a.to_ulong())<<endl;

    // 忽略了低位的1
    cout<<"b"<<endl;
    bitset<7> b("10000011");
    cout<<b.count()<<endl;
    cout<<b.to_ulong()<<endl;
    cout<<sizeof(b.to_ulong())<<endl;

//    cout<<"c"<<endl;
//    bitset<8> c("12345678");
//    cout<<c.count()<<endl;
//    cout<<c.to_ulong()<<endl;
//    cout<<sizeof(c.to_ulong())<<endl;

//    cout<<"d"<<endl;
//    bitset<8> d("01010189");
//    cout<<d.count()<<endl;
//    cout<<d.to_ulong()<<endl;
//    cout<<sizeof(d.to_ulong())<<endl;

    //terminate called after throwing an instance of 'std::invalid_argument'
    //  what():  bitset::_M_copy_from_ptr
//    cout<<"e"<<endl;
//    bitset<8> e("asd10110");
//    cout<<e.count()<<endl;
//    cout<<e.to_ulong()<<endl;
//    cout<<sizeof(e.to_ulong())<<endl;

    //忽略了高位的0，取低位的64位
    cout<<"f"<<endl;
    bitset<65> f("00000000000000000000000000000000000000000000000000000000000000001");
    cout<<f.count()<<endl;
    cout<<f.to_ulong()<<endl;
    cout<<sizeof(f.to_ulong())<<endl;

    //取了前65位的0，忽略了第66位的1
    cout<<"g"<<endl;
    bitset<65> g("000000000000000000000000000000000000000000000000000000000000000001");
    cout<<g.count()<<endl;
    cout<<g.to_ulong()<<endl;
    cout<<sizeof(g.to_ulong())<<endl;

    //terminate called after throwing an instance of 'std::overflow_error'
    //  what():  _Base_bitset::_M_do_to_ulong
//    cout<<"h"<<endl;
//    bitset<65> h("10000000000000000000000000000000000000000000000000000000000000001");
//    cout<<h.count()<<endl;
//    cout<<h.to_ulong()<<endl;
//    cout<<sizeof(h.to_ulong())<<endl;

    cout<<"i"<<endl;
    bitset<2> i("1101");
    cout<<i.count()<<endl;
    cout<<i.to_ulong()<<endl;
    cout<<sizeof(i.to_ulong())<<endl;

    // 猜测，你指定位数n，取给的字符串的前n位，去初始化bitset的每一位。
    // 对于to_ulong,从低位不断乘2^i，累计得到最终的数值结果，过大会产生溢出错误
    // 对于to_ullong同样
    return 0;
}