Question

1. Design c++ program so that it correctly meets the program specifications given below.  

Specifications: Create a menu-driven program that finds and displays areas of 3 different objects. The menu should have the following 4 choices: 1 -- square 2 -- circle 3 -- right triangle 4 -- quit If the user selects choice 1, the program should find the area of a square. If the user selects choice 2, the program should find the area of a circle. If the user selects choice 3, the program should find the area of a right triangle. If the user selects choice 4, the program should quit without doing anything. If the user selects anything else (i.e., an invalid choice) an appropriate error message should be printed.

Sample Run Program to calculate areas of objects         1 -- square         2 -- circle         3 -- right triangle         4 -- quit 2 Radius of the circle: 3.0 Area = 28.2743

Answer 1

I have written two codes separately with output-

code 1- if you want the menu to appear again instead of program getting exit just after one choice this is your code.

#include<iostream>
#include<stdlib.h>
using namespace std;
  

int main()
{
int choice; //choice variable for the options to choose
   float radius,area,length,width; //variable used for area calculations

   do //do loop begins from here
{

   std::cout << "Please to calculate areas of objects\n"; //menu outputs
   std::cout << "1 -- Square\n";
   std::cout << "2 -- Circle\n";
   std::cout << "3 -- Right triangle\n";
   std::cout << "4 -- Quit\n";

std::cin >> choice; //choice input from the menu

   switch(choice) //switch case for doing the operqations on the basis of user choice
{
case 1:   
std::cout << "Enter length of square: ";
std::cin >> length;
std::cout << "Area=" << length*length << "\n\n";
break;
case 2:
std::cout << "Enter the radius of the circle: ";
std::cin >> radius;
area = 3.142 * radius * radius;
cout << "Area="<<area<< "\n\n";
break;
case 3:
std::cout << "Enter the length of the right triangle:";
std::cin >> length;
std::cout << "Enter the width of the right triangle: ";
std::cin >> width;
std::cout << "Area=" << length*width/2 << "\n\n";
break;

case 4:
exit(0);
break;

default: //invalid choice message
cout<<"Invalid choice"<< "\n\n";
}

} while(choice!=4); //while with condition or quit option number 4
return 0;
}

code 2- if you don't want the menu to reappear and program should just execute one operation and exit.

#include<iostream>
#include<stdlib.h>
using namespace std;
   int main()
{
int choice;   //choice variable for the options to choose
   float radius,area,length,width;   //variable used for area calculations

   std::cout << "Please to calculate areas of objects\n"; //menu outputs
   std::cout << "1 -- Square\n";
   std::cout << "2 -- Circle\n";
   std::cout << "3 -- Right triangle\n";
   std::cout << "4 -- Quit\n";

std::cin >> choice; //choice input from the menu

   switch(choice)
{
case 1:
std::cout << "Enter length of square: ";
std::cin >> length;
std::cout << "Area=" << length*length << "\n\n";
break;
case 2:
std::cout << "Enter the radius of the circle: ";
std::cin >> radius;
area = 3.142 * radius * radius;
cout << "Area="<<area<<"\n\n";
break;
case 3:
std::cout << "Enter the length of the right triangle:";
std::cin >> length;
std::cout << "Enter the width of the right triangle: ";
std::cin >> width;
std::cout << "Area=" << length*width/2 << "\n\n";
break;

case 4:
exit(0);
break;

default:
cout<<"Invalid choice"<<"\n\n";    //invalid choice message
}

return 0;
}

If you still have any query reguarding this code, do reply.