Infinite loop when user enters char

[sinatra87]

I've search the forums here and found a few other people with the same problem I have, but I'm not sure I understand the solutions that have been presented.

I have a simple geometry calculator I'm working on as C++ practice. My program displays a menu and asks for the user to input a number to select a function. When the user enters a character instead of a number the program loops endlessly.

Is there a simple way to catch the char input and ask the user to fix his choice, similar to the way my program handles a user entering a number that isn't in the menu?

#include <iostream>
#include <cmath>
using namespace std;

void wiseass();
void square();
void circle();
void triangle();
    
double 
    choice,
    length,
    radius,
    area,
    base,
    height;
    
int main() {

//Introduce the program and get the user's choice
    cout << "This is a simple geometry calculator.\n";
    cout << "Would you like to find the area of a:\n";
    cout << "(1) Square\n";
    cout << "(2) Circle?\n";
    cout << "or\n";
    cout << "(3) Triangle?\n\n";
    cout << "Please type the number that corresponds to your selection =>   ";
    cin >> choice;
    
    //Give the wiseass a chance to get his selection right
    while (choice != 1 && choice != 2 && choice != 3 && choice !=42) 
        {
        wiseass(); //call wiseass function
        }
    
    // (1) Call function for area of square
    if (choice == 1)
        { square(); } 
        
    // (2) Call function for area of circle
    else if (choice == 2) 
        { circle(); }
        
    // (3) Call function for area of triangle
    else if (choice == 3) 
        { triangle(); }
    
    //Easter egg
    else if (choice == 42) 
        {
        cout << "\n42 is the ultimate answer to life, the universe, and everything. Since you already possess this answer, you obviously don't need this calculator. Goodbye!";
        }
        
    cout << "\n\n<END PROGRAM>\n\n";
    
    return 0;
}



//###############################
//# When Dealing with a wiseass #
//###############################
void wiseass()
    {

        //If he enters a negative number
        if (choice < 1) 
            {
            cout << "\n\nThese are POSITIVE numbers, as in, GREATER than zero. Try it again...\n\n";
            }
    
        //If he enters a number not in the menu
        else if (choice > 3 && choice != 42) 
            {
            cout << "\nTry entering a number that's actually in the menu...\n\n";
            }

        //Display the menu again
        cout << "Would you like to find the area of a:\n";
        cout << "(1) Square\n";
        cout << "(2) Circle?\n";
        cout << "or\n";
        cout << "(3) Triangle?\n\n=>   ";
        cin >> choice;
    }


//##################################
//# (1) Solve the area of a square #
//##################################
void square()
     {
        cout << "\n\nPlease enter the length of the sides =>   ";
        cin >> length;
        
        //solve
        area=length*length;
        
        //Display result
        cout << "\nThe area of your square is: " << area << endl;
     }


//##################################
//# (2) Solve the area of a circle #
//##################################
void circle()
    {
        cout << "\n\nPlease enter the radius of your circle =>   ";
        cin >> radius;
            
        //solve
        area=pow(3.14*radius, 2);
            
        //Display result
        cout << "\nThe area of your circle is: " << area << endl;
    }
    

//####################################
//# (3) Solve the area of a triangle #
//####################################
void triangle()
    {
        cout << "\nPlease enter the length of your triangle's base =>   ";
        cin >> base;
        cout << "\nPlease enter your triangle's height =>   ";
        cin >> height;

        //solve
        area=(base*height)/2;

        //Display result
        cout << "\nThe area of your triangle is: " << area << endl;
    }

Be gentle. I'm a noob. ;(

[WaltP]

Is there a simple way to catch the char input and ask the user to fix his choice, similar to the way my program handles a user entering a number that isn't in the menu?

Read all your inputs as strings. Test the string for all digits. If correct, convert the string to a value and continue.

[minor rant]

Be gentle. I'm a noob. ;(

This is and always has been one of the most obnoxious requests we get. What makes you think we can't tell you are a noob? Doesn't your question already implicitly state it? :icon_rolleyes:
[/minor rant]

[sinatra87]

Thank you kindly. Easy enough. :)