pls explain this program

Question

#include <iostream>

using namespace std;

int main()
{
    int Menu;
    double pi = 3.14159265;
    double A, r, h, g, a, b;
    // A = Area
    // r = radius
    // h = height
    // g = baseline of the Triangle
    // a = 1st side of the Rectangle
    // b = 2nd side of the Rectangle
    
    do{
        
        
        cout << "\nChoose an option: ";
        cout << "";
        cout << " 1 = Circle";
        cout << " 2 = Rectangle ";
        cout << " 3 = Triangle  ";
        cout << " 4 = End       ";
        cout << "" << endl;
        cin >> Menu;
        
        if(Menu == 1){
            cout << "\nCalculate the Area of a circle";
            cout << "\nType in the value for r: ";
            cin >> r;
            A = r * r * pi;
            cout << "The Area of the circle is: " << A;
        }
                
        if(Menu == 2){
            cout << "\nCalculate the Area of a rectangle: ";
            cout << "\nType in the value of a: ";
            cin >> a;
            cout << "Type in the value of b: ";
            cin >> b;
            A = a * b;
            cout << "The Area of the rectangle is: " << A;
        }
                
        if(Menu == 3){
            cout << "\nCalculate the Area of a Triangle: ";
            cout << "\nType in the value for the height h: ";
            cin >> h;
            cout << "Type in the value for g: ";
            cin >> g;
            A = 0.5 * g * h;
            cout << "The Area of the triangle is: " << A;
        }
                
        if(Menu == 4){
            cout << "\nThe End!";
        }    
        
        if(Menu > 4){
            cout << "Error! Not a valid option!";
        }
        
    }while(Menu != 4);

    return 0;
}

Answer 1

Hello,

It is a very simple program.

coding language is c++. Based on the user input snippet will calculate the area of  circle,rectangle,Triangle.

Comments

#include <iostream>
//-> including the standard libraries

using namespace std;
//-> this is useful for beginners you dont need to write std:: e.g.: std::cout<<" ";



int main()  //-> this is where your main function starts all your code goes inside of it you will learn more about functions as you progress
{
    int Menu;                   //Variable for the Menu
    double pi = 3.14159265;     //Variable for pi
    double A, r, h, g, a, b;
    // Variable for:
    // A = Area
    // r = radius
    // h = height
    // g = baseline of the Triangle
    // a = 1st side of the Rectangle
    // b = 2nd side of the Rectangle
    
    do{             //-> this starts a loop as long as the user doesnt input 4 for the variable Menu it will always stay in this loop see the while statement at the end
        
        //cout is printing the following lines to the console window
        cout << "\nChoose an option: ";
        cout << "";
        cout << " 1 = Circle";
        cout << " 2 = Rectangle ";
        cout << " 3 = Triangle  ";
        cout << " 4 = End       ";
        cout << "" << endl;
        cin >> Menu;        //cin reads an input from the console to a variable (here the Variable is Menu)
        
        if(Menu == 1){
            //if Variable Menu has the Value 1 (if the user inputs 1), it will run the following code:
            cout << "\nCalculate the Area of a circle";
            cout << "\nType in the value for r: ";
            cin >> r;
            A = r * r * pi;
            cout << "The Area of the circle is: " << A;
            //Calculates the Area of a circle and prints the result onto the screen
        }
                
        if(Menu == 2){
            //if Variable Menu has the Value 2 (if the user inputs 2), it will run the following code:
            cout << "\nCalculate the Area of a rectangle: ";
            cout << "\nType in the value of a: ";
            cin >> a;
            cout << "Type in the value of b: ";
            cin >> b;
            A = a * b;
            cout << "The Area of the rectangle is: " << A;
            //Calculates the Area of a rectangle and prints the result onto the screen
        }
                
        if(Menu == 3){
            //if Variable Menu has the Value 3 (if the user inputs 3), it will run the following code:
            cout << "\nCalculate the Area of a Triangle: ";
            cout << "\nType in the value for the height h: ";
            cin >> h;
            cout << "Type in the value for g: ";
            cin >> g;
            A = 0.5 * g * h;
            cout << "The Area of the triangle is: " << A;
            //Calculates the Area of a triangle and prints the result onto the screen
        }
                
        if(Menu == 4){
            //if Variable Menu has the Value 4 (if the user inputs 4), it will run the following code:
            cout << "\nThe End!";
            //Prints The End to the Screen
        }    
        
        if(Menu > 4){
            //if Variable Menu is bigger than 4 (if the user inputs something bigger than 4), it will run the following code:
            cout << "Error! Not a valid option!";
            //this part is basic error handling
        }
        
    }while(Menu != 4);
    //the code in the do{}while(); will run as long as the user doenst input the value 4 for the Variable Menu

    return 0;
}