Printing decimal precision upto desiired number in cpp

Question

I have an application I want to print the precision of the calculated prime number up to the desired number. But the number is omitted on the terminal as shown below.

The code I used for this is as

 int  main ()
{
    cout << "Enter the precision for calculation" << endl;
    long num_steps ;
    cin >> num_steps ;
    cout << "Precision = " << num_steps << endl;

    double step;
    double  x=0.0, pi, sum = 0.0;

    cout << "Enter the number of CPU core involved in calculation" << endl;
    int numberOfCpuCore = 0;
    cin >> numberOfCpuCore;

    int i;

    step = 1.0l/( double) num_steps;


        }
    pi = step * sum;
    printf("Pi value = %.10le\n", pi);
return 0;

}

My question is how can I print the precision to the desired number as entered from the command line.

Answer 1

use iomanip. first add #include <iomanip> and then std::setprecision(num_steps) like this program:

This code was written based on Calculate Pi from Geeks For Geeks.

#include <cstdio>
#include <iostream>
#include <iomanip>
using namespace std;

int  main()
{
// Initialize denominator
    double  k = 1;

// Initialize sum
    double  s = 0;

    for (auto i(0); i < 10000; i++)
    {
        if (i % 2 == 0)
        {
            s += 4 / k;
        }
        else
        {
            s -= 4 / k;
        }

// denominator is odd
        k += 2;
    }

    cout << "Pi value =" << std::setprecision(k) << s << endl;

// printf("Pi value = %.10le\n", pi);
    return 0;
}

This will be the output: