#include <iostream>
#include <iomanip>

#include <cmath>

using namespace std;


int main() {

    float x = 1.0e-20f;
    float y =2.7e20f;
    float z {0.123f};
    
    cout << "x = "  << x << endl;
    cout << " pi = " << M_PI << endl;
    cout << "y = " << y << endl;
    cout << "z = " << z << endl;

    cout << endl << endl;
    cout << " cout << scientific " << endl;
    cout << scientific;
    cout << "x = "  << x << endl;
    cout << " pi = " << M_PI << endl;
    cout << "y = " << y << endl;
    cout << "z = " << z << endl;

    cout << endl << endl;
    cout << " cout << fixed " << endl;
    cout << fixed;
    cout << "x = "  << x << endl;
    cout << " pi = " << M_PI << endl;
    cout << "y = " << y << endl;
    cout << "z = " << z << endl;

    cout << endl << endl;
    cout << setprecision(3);
    cout << " cout << setprecision(3)  " << endl;
    cout << "x = "  << x << endl;
    cout << " pi = " << M_PI << endl;
    cout << "y = " << y << endl;
    cout << "z = " << z << endl;


    int spaces{10};

    cout << endl << endl;
    cout << setw(spaces);
    cout << " cout << setw( " << spaces << ")  " << endl;
    cout << "x  = " << setw(spaces)  << x << endl;
    cout << "pi = " << setw(spaces) << M_PI << endl;
    cout << "y  = " << setw(spaces) << y << endl;
    cout << "z  = "  << setw(spaces)<< z << endl;

    return 0;
}