格式化输入输出

#include<iostream>

#include<cmath>

#include<iomanip>

using namespace std;



int main()

{

    cout<<"default bool values: "<<true<<" "<<false<<"\nalpha bool value: "<<boolalpha<<true<<" "<<false<<endl;

    cout<<noboolalpha<<endl;

    cout<<"default: "<<20<<" "<<1924<<endl;

    cout<<"octal: "<<oct<<20<<" "<<1024<<endl;

    cout<<"hex: "<<hex<<20<<" "<<1024<<endl;

    cout<<"decimal: "<<dec<<20<<" "<<1024<<endl;

    cout<<endl;

    cout<<showbase;

    cout<<uppercase<<"default: "<<20<<" "<<1924<<endl;

    cout<<uppercase<<"octal: "<<oct<<20<<" "<<1024<<endl;

    cout<<uppercase<<"hex: "<<hex<<20<<" "<<1024<<endl;

    cout<<uppercase<<"decimal: "<<dec<<20<<" "<<1024<<endl;

    cout<<nouppercase<<noshowbase;

    cout<<showbase<<"hex: "<<hex<<20<<" "<<1024<<noshowbase<<endl;

    cout<<dec;

    cout<<endl;

    cout<<"precision: "<<cout.precision()<<",Value: "<<sqrt(2.0)<<endl;

    cout.precision(12);

    cout<<"precision: "<<cout.precision()<<",Value: "<<sqrt(2.0)<<endl;

    cout<<setprecision(3);

    cout<<"precision: "<<cout.precision()<<",Value: "<<sqrt(2.0)<<endl;

    cout<<"default format: "<<100*sqrt(2.0)<<'\n'

        <<"scientific: "<<scientific<<100*sqrt(2.0)<<'\n'

        <<"fixed decimal: "<<fixed<<100*sqrt(2.0)<<'\n';

       // <<"hexadecimal: "<<std::hexfloat<<100*sqrt(2.0)<<'\n'

        //<<"use defaults: "<<defaultfloat<<100*sqrt(2.0)<<"\n\n"

    cout<<endl;

    int i=-16;

    double d=3.14159;

    cout<<"i: "<<setw(12)<<i<<"next col"<<'\n'

        <<"d: "<<setw(12)<<d<<"next col"<<'\n';

    cout<<left

        <<"i: "<<setw(12)<<i<<"next col"<<'\n'

        <<"d: "<<setw(12)<<d<<"next col"<<'\n'

        <<right;

    cout<<right

        <<"i: "<<setw(12)<<i<<"next col"<<'\n'

        <<"d: "<<setw(12)<<d<<"next col"<<'\n';

    cout<<internal

        <<"i: "<<setw(12)<<i<<"next col"<<'\n'

        <<"d: "<<setw(12)<<d<<"next col"<<'\n';

    cout<<setfill('#')

        <<"i: "<<setw(12)<<i<<"next col"<<'\n'

        <<"d: "<<setw(12)<<d<<"next col"<<'\n'

        <<setfill(' ');

    char ch;

    cin>>noskipws;

    while(cin>>ch)

        cout<<ch;

    cin>>skipws;

}