2023 5 13

#include <iostream>
#include <iomanip>
#include <bitset>
using namespace std;
int main()
{
    double n = 3.1415926;

#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
    int n;
    cin >> n;
    cout.setf(ios::showbase);
    cout << "十进制：" << n << endl;
    cout.unsetf(ios::dec);
    cout.setf(ios::oct);
    cout << "八进制：" << n << endl;
    cout.unsetf(ios::oct);
    cout.setf(ios::hex);
    cout << "十六进制：" << n << endl;
    return 0;
}

#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
int main()
{
    double n = 3.1415926;
    cout.setf(ios::internal);
    cout.precision(8);
    cout << n << endl;
    cout.precision(6);
    cout << n << endl;
    cout.precision(4);
    cout << n << endl;
    return 0;
}

    cout << setiosflags(ios::fixed) << setprecision(8) << n << endl;
    cout << setiosflags(ios::fixed) << setprecision(6) << n << endl;
    cout << setiosflags(ios::fixed) << setprecision(4) << n << endl;
    cout << bitset<2>(n) << endl;
    return 0;
}