questions.cpp

#include<iostream>
#include<iomanip>
using namespace std;
int main(){
    double x1 = 0.123456, x2 = 23.987, x3 = 123.456;
    //a
    cout<<left<<setw(15)<<x1<<endl;
    //b
    cout<<fixed<<setprecision(2)<<right<<setw(12)<<x2<<endl;
    //c
    cout<<scientific<<setprecision(4)<<x3<<endl;
    return 0;
}