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

    
main()
{
      double pi1;
      double pi2;
      double termspi;
      double currentpi;
      int counter;
      int steps;
      
      
      cout << fixed << showpoint << setprecision(9) << endl;
      
      pi1 = (4);
      pi2 = ();
      int three;
      
      cout << "Program will approximate Pi" << endl;                            
      
      
      
      cout << "Enter the number of terms to use: ";
      cin >> termspi;
      cout << endl;
      
      if (termspi == 1)
          currentpi = pi1;
      else if (termspi == 2)
               currentpi = pi2;
      else
      {
          counter = 3;
          three = 3;
          
          while (counter <= termspi)
          {
               currentpi = ((three + 2) /4);
               three = pi1;
               pi1 = pi2;
               pi1 = currentpi;
               counter++;
          }
      }
      
      cout << "The approximation of pi at position " << termspi << " is" << currentpi << endl;
      
          
      
      
    
      


cout << endl <<endl;
    cout << "Press [enter] to exit" << endl;
    cin.ignore();
    cin.get();
return 0;

      }

long i;
for (i=1; i<(2*termspi-1); i+=2) {
    //  do calulations here
}

#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

    void printMessage(string);
    int returnNumber(string);

int main()
{
    char again;
    int termspi,
        steps,
        num;
    
    int countDenominator;
    float pi;    
    const double NUMERATOR = 4.0;
    
    cout << " Program will approximate Pi ";
    cout << endl << endl;    
        

    termspi = returnNumber ("Enter the number of terms to use: ");
    cout << endl << endl;
    
      
for (int num = 1; num <=(2*termspi-1); num += 2){
    if  ((num-1)%4 != 0)
    cout << 4.0 /-num << endl;
    else
    cout << 4.0/num << endl;
}

    steps = returnNumber("Display Pi after every how many steps?: ");


int count = 1;


while (steps < termspi) {
    steps += 2 * count;
    count += 1;
}
cout << "num = " << steps << endl;
cout << "count = " << count << endl;





do {
        cout << "Enter Y to run program again" << endl;
        cout << "(or any other key to exit)" << endl;
        cin >> again;
    } while ((again == 'Y') || (again == 'y'));
    return 0;
}

void printMessage(string msg)
   {
     cout << msg;
   }

int returnNumber(string msg)
   {
     int num;
     cout << msg;
     cin >> num;
     while (num < 1){
         cout << "Your input is not valid !!!" << endl;
         cout << "Please Re-enter a positive non zero number: ";
         cin >> num;}
         cout << endl;
     return num;
  
}

int main(int argc, char *argv[])
{
    long n;
    float pi;
    int pos;
    
    for (n=1; n <= 99999999; n++)
     {
        if ( (n % 2) == 0 ) {
           pos = -1;
           }
        else   {
            pos = 1;
            }
            
        pi = pi + (float) (4*pos)/(2*n-1);
        }