Question

A) One of the problems that have been discussed in the class is to write a simple C++ program to determine the area and circumference of a circle of a given radius. In this lab you will be rewriting the program again but this time you will be writing some functions to take care of the user input and math. Specifically, your main function should look like the following:

int main()

{

double radius; double area;
double circumference;

//the radius of the circle
//the area of the circle
//the circumference of the circle

//get the value of the radius from the user radius = getRadius();

//determine the area and circumference area = findArea(radius);
circumference = findCircumference(radius);

//output the results
cout << "A circle of radius " << radius << " has an area of: " << area <<endl; cout << "and a circumference of: "<< circumference << endl;

system("PAUSE");

return 0; }

Your job will be to write these three functions:

1. 1) getRadius
   This function should ask the user to enter the value for the radius and return that value.

2. 2) findArea
   This function should take the radius as a parameter and calculate and return the area. (Hint: area = 3.14159*radius*radius)

3. 3) findCircumference
   This function should take the radius as a parameter and calculate and return the circumference. (Hint: circumference = 2*3.14159*radius)

OPTIONAL: Use prototypes for your functions. Place the prototypes before main (but after the using namespace std; line) and place the actual functions after the main function.

A sample run of your program should look like this (bold bracketed text stands for user input):

Enter the radius of the circle: [3.5]
A circle of radius 3.5 has an area of: 38.4845 and a circumference of: 21.9911
Press any key to continue . . .

                       Submit The Program Online

B) Function parameter passing: Pass By value and pass by reference

// This program takes two numbers (payRate & hours) // and multiplies them to get grosspay.
// It then calculates net pay by subtracting 15%

#include <iostream>
#include <iomanip>
using namespace std;
//Function prototypes
void printDescription();
void computePaycheck(float, int, float&, float&);

int main()
{
float payRate;
float grossPay;
float netPay;
int hours;
cout << setprecision(2) << fixed;
cout << "Welcome to the Pay Roll Program" << endl;

//Call to Description function

cout << "Please cin >> payRate; cout << endl << cin >> hours; cout << endl <<

input the pay per hour" << endl;
"Please input the number of hours worked" << endl; endl;

//Call to computePaycheck function
// Fill in the code to output grossPay and netPay

return 0; }

void printDescription() // The function heading
{
cout << "************************************************" << endl << endl; cout << "This program takes two numbers (payRate & hours)" << endl;
cout << "and multiplies them to get gross pay " << endl;
cout << "it then calculates net pay by subtracting 15%" << endl;
cout << "************************************************" << endl << endl; }

• // *********************************************************************

• // computePaycheck //

• // task: This function takes rate and time and multiples them to

• // get gross pay and then finds net pay by subtracting 15%.

• // data in: pay rate and time in hours worked

• // data out: the gross and net pay //

• // ******************************************************************** void computePaycheck(float rate, int time, float& gross, float& net)
  {
  // Fill in the code to find gross pay and net pay

}

Exercise 1: Fill in the code (places in bold) and note that the function pay. Both gross and net are returned to the main()function where those values are printed.

Exercise 2: Compile and run your program with the following data and make sure you get the output shown.

Please input the pay per hour

9.50

Please input the number of hours worked

40

The gross pay is $380 The net pay is $323

Answer 1

A.

#include <iostream>

#include <stdlib.h>

using namespace std;

//Function prototypes

double findArea(double radius);

double getRadius();

double findCircumference(double radius);

int main()

{

double radius;

double area;

double circumference;

//the radius of the circle

//the area of the circle

//the circumference of the circle

//get the value of the radius from the user

radius = getRadius();

//determine the area and circumference

area = findArea(radius);

circumference = findCircumference(radius);

//output the results

cout << "A circle of radius " << radius << " has an area of: " << area << endl;

cout << "and a circumference of: " << circumference << endl;

system("PAUSE");

return 0;

}

double getRadius()

{

double radius;

cout << "Enter the radius of the circle: ";

cin >> radius;

return radius;

}

double findArea(double radius)

{

//return the area of the circle

return 3.14159 * radius * radius;

}

double findCircumference(double radius)

{

//return the circumference

return 2 * 3.14159 * radius;

}

OUTPUT

B

// This program takes two numbers (payRate & hours) // and multiplies them to get grosspay.

// It then calculates net pay by subtracting 15%

#include <iostream>

#include <iomanip>

using namespace std;

//Function prototypes

void printDescription();

void computePaycheck(float, int, float &, float &);

int main()

{

float payRate;

float grossPay;

float netPay;

int hours;

cout << setprecision(2) << fixed;

cout << "Welcome to the Pay Roll Program" << endl;

//Call to Description function

printDescription();

cout << "input the pay per hour " << endl;

cin >> payRate;

cout << "Please input the number of hours worked" << endl;

cin >> hours;

//Call to computePaycheck function

computePaycheck(payRate, hours, grossPay, netPay);

// Fill in the code to output grossPay and netPay

cout << "The gross pay is $" << grossPay << " The net pay is $" << netPay << endl;

return 0;

}

void printDescription() // The function heading

{

cout << "************************************************" << endl

<< endl;

cout << "This program takes two numbers (payRate & hours)" << endl;

cout << "and multiplies them to get gross pay " << endl;

cout << "it then calculates net pay by subtracting 15%" << endl;

cout << "************************************************" << endl

<< endl;

}

// *********************************************************************

// computePaycheck //

// task: This function takes rate and time and multiples them to

// get gross pay and then finds net pay by subtracting 15%.

// data in: pay rate and time in hours worked

// data out: the gross and net pay //

// ********************************************************************

void computePaycheck(float rate, int time, float &gross, float &net)

{

// Fill in the code to find gross pay and net pay

gross = rate * time;

net = gross - 0.15 * gross;

}

OUPUT