/* Title      - Calculating Powers
 * File name  - Lab16
 * Programmer - 415 Erich Musick
 * IPO        - Input   - User inputs the base and exponent of a power
 *              Process - Value of base raised to the power is calculated
 *              Output  - Result, and values inputed by user are displayed
*/

/*************************** H E A D E R  F I L E S ***************************/
//#include "iostream.h"
#include "waittoclose.h"    // Add to project waittoclose.cpp
#include "apstring.h"       // Add to project apstring.cpp
//#include "randgen.h"       // Add to project randgen.cpp
#pragma hdrstop
//#include "apvector.h"     // DO NOT ADD TO PROJECT apvector.cpp
//#include "apmatrix.h"     // DO NOT ADD TO PROJECT apmatrix.cpp

/******************** F U N C T I O N  P R O T O T Y P E S ********************/
void getValues(double &x, int &n);
double raiseToPower(double x, int n);
void displayResult(double x, int n, double result);

/****************************** F U N C T I O N S *****************************/
// GET VALUES
 /* purpose    - Get the values the user would like to use for the base and the
  *               exponent
  * parameters - x - reference parameter of type double containing the base
  *            - n - reference parameter of type int contaning the exponent
  * input      - x - value of the base; n - value of the exponent
  * process    - None.
  * output     - None.
  * return     - None.
  */
void getValues(double &x, int &n) {
  cout << "Enter the real number base: ";
  cin >> x;
  cout << "Enter the power to raise to: ";
  cin >> n;

  return;
}

// RAISE TO POWER
 /* purpose    - Calculate the value of the base raised to the power
  * parameters - x - value parameter of type double containing the base
  *            - n - value parameter of type int contaning the exponent
  * input      - None.
  * process    - Using iterative statments, the value of the base raised to the
  *               power is calculated
  * output     - None.
  * return     - result - a variable of type double containing the value of the
  *               base raised to the power
  */
double raiseToPower(double x, int n) {
  int count;
  double result;

  if (n >= 0) {           // We're raising the base to a positive exponent
    for (count = 1, result = 1.; count <= n; count++) {
      result = result * x;
    }
  }
  else {                  // We're raising the base to a negitive exponent
    n = n * -1;
    for (count = 1, result = 1.; count <= n; count++) {
      result = result * (1. / x);
    }
  }

  return result;
}

// DISPLAY RESULT
 /* purpose    - Display the result, as well as the values entered by the user
  * parameters - x - value parameter of type double containing the base
  *            - n - value parameter of type int contaning the exponent
  *            - result - value parameter of type double containing the result
  *               of the base raised to the power
  * input      - None.
  * process    - None.
  * output     - Values entered by user, as well as the result, are displayed.
  * return     - None.
  */
void displayResult (double x, int n, double result) {
  cout << endl;
  cout << "(";
  cout << x;
  cout << ")^";
  cout << n;
  cout << " = ";
  cout << result;
  cout << endl;
  cout << endl;

  return;
}

int main() {
  apstring goAgain;         // Contains user input (calculate another?)
  double base;              // Base of power
  int power;                // Power that program will raise base to
  double result;            // Variable that contains result of base^power

  cout << "CALCULATING POWERS";
  cout << endl;
  cout << "Calculates the value of a real number base raised to an integer ";
  cout << "power.";
  cout << endl;
  cout << endl;

  do {
    // USER INPUT: get values for base and power
    getValues(base,power);

    // CALCULATION: calculate the value of the base raised to the power
    result = raiseToPower(base,power);

    // DISPLAY: display the result of the calculation
    displayResult(base,power,result);

    // USER INPUT: Loop through again?
    cout << "Again (y/n)? ";
    cin >> goAgain;

    // DISPLAY: Leave an extra space if user would like to loop through again.
    if (goAgain == "y" || goAgain == "Y") {
      cout << endl;
    }
  } while (goAgain == "y" || goAgain == "Y");

  return 0;
}

/************************** S A M P L E  O U T P U T **************************/

/*               LAB16 by 415 ERICH MUSICK   11:24 on Nov 19 2001

CALCULATING POWERS
Calculates the value of a real number base raised to an integer power.

Enter the real number base: -1.2
Enter the power to raise to: 2

(-1.2)^2 = 1.44

Again (y/n)? y

Enter the real number base: 2
Enter the power to raise to: 3

(2)^3 = 8

Again (y/n)? y

Enter the real number base: 5
Enter the power to raise to: 3

(5)^3 = 125

Again (y/n)? y

Enter the real number base: 10
Enter the power to raise to: -10

(10)^-10 = 1e-10

Again (y/n)? y

Enter the real number base: 2
Enter the power to raise to: -2

(2)^-2 = 0.25

Again (y/n)? y

Enter the real number base: 2
Enter the power to raise to: 0

(2)^0 = 1

Again (y/n)? n

'Esc' closes window.*/