Exercise 4.1: projectile-2.0.cpp

//projectile-2.0.cpp
//Solution to Exercise 4.1

//Adapts projectile-1.0.cpp to read and write to files 
//instead of the console.

//Program to calculate the time of flight and distance
//travelled by a projectile launched from ground level.
//Reads in magnitude, in m/s, and angle, in degrees,
//of initial velocity from a file named projectile_data.in
//Outputs the time of flight and horizontal distance travelled 
//to a file named projectile_data.out
//Steven Bamford

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

int main()
{
  double v_mag;          //initial velocity magnitude (m/s)
  double v_angle_deg, v_angle_rad; //initial velocity angles
  double v_x, v_y;       //and cartesian components
  double t, x;           //time of flight and distance
  const double g = 9.8;  //acc. due to gravity, m/s
  ifstream fin;     //input data file stream
  ofstream fout;    //output data file stream

  //open files
  fin.open("projectile_data.in");
  fout.open("projectile_data.out");

  //loop through data
  while (true)
    {
      //read initial velocity parameters
      fin >> v_mag >> v_angle_deg; 

      //break if end of file reached
      if (fin.eof()) break;

      //convert angle to radians
      v_angle_rad = v_angle_deg * M_PI / 180.0;
      
      //convert velocity to cartesian components
      v_x = v_mag * cos(v_angle_rad);
      v_y = v_mag * sin(v_angle_rad);
      
      //calculate flight parameters
      t = 2.0 * v_y / g;  //total time of flight
      x = v_x * t;        //total horizontal distance travelled
      
      //output flight parameters to screen
      fout.setf(ios::fixed, ios::floatfield);
      fout.precision(2);
      fout << t << "  " << setw(8) << x << endl;
    }

  //close files
  fin.close();
  fout.close();

  return(0);
}