C++ Question on exiting program from loop

[crouse]

Okay......... keep in mind I'm still learning so don't beat me up to much.

My question is when the program shown below runs..........it works great. UNLESS you type a letter key or something other than a number to exit. If you hit a letter then enter........it goes on forever... what should be included in the code to eliminate the "bug" in the code.......... or a better way to do the loop and exit when needed???
------------------------------

#include <iostream>

using namespace std;

/* This is to Figure the Area of a Circle,
 Added a loop to this to allow for continued use
until the program encounters another number besides 1 */

float areaofcircle (float x, float y)
{

return ((x*x)*y);
}

int main();
int main()
{

int looping;


     do
     {
     cout << "\n";
     cout << "\n";
     cout << "******************************************** \n";
     cout << "******************************************** \n";
     cout << "\n";
     cout << "\n";
     cout << " AREA OF A CIRCLE \n";
     cout << "\n";
     cout << "\n";
     cout << "To figure the area of a circle we need to \n";
     cout << "have the radius and pi. \n";
     cout << "The formula for the area of a circle is :\n";
     cout << " PI X Radius(2) = AREA \n";
     float a, b, c ;
     cout << "\n";
     cout << "Please enter the Radius of the circle: ";
     cin >> a;
     cout << "PI=3.1415 (for our purposes here): ";
     b=3.1415 ;
     cout << "\n";
     cout << "\n";
     c=areaofcircle(a,b);
     cout << "The AREA of the circle with a radius of " << a << " is " << c << " \n";
     cout << "\n";
     cout << "\n";
     cout << "Would you like to do this again?? \n";
     cout << "Type 1 to continue, or 0 to exit| \n";
     cin >> looping;

     }while ( looping == 1 );

cout << "\n";
cout << "Thanks for using my Area of a Circle program !! \n";
cout << "Good Bye !!\n";
cout << "******************************************** \n";
cout << "******************************************** \n";
cout << "\n";
cout << "\n";


return 0;
}

------------------------------
The code is also posted here : http://www.crouse.ws/viewtopic.php?topic=97&forum=22

Thanks.

[crouse]

Figured it out

#include <iostream>
using namespace std;

/* This is to Figure the Area of a Circle,
 Added a loop to this to allow for continued use
until the program encounters another number besides 1 */

float areaofcircle (float x, float y)
{return ((x*x)*y);}

int main()
{

int looping;

     do{
          cout << "\n";
          cout << "\n";
          cout << "******************************************** \n";
          cout << "******************************************** \n";
          cout << "\n";
          cout << "\n";
          cout << " AREA OF A CIRCLE \n";
          cout << "\n";
          cout << "\n";
          cout << "To figure the area of a circle we need to \n";
          cout << "have the radius and pi. \n";
          cout << "The formula for the area of a circle is :\n";
          cout << " PI X Radius(2) = AREA \n";
          float a, b, c ;
          cout << "\n";
          cout << "Please enter the Radius of the circle: ";
          cin >> a;
          cout << "PI=3.1415 (for our purposes here): ";
          b=3.1415 ;
          cout << "\n";
          cout << "\n";
          c=areaofcircle(a,b);
          cout << "The AREA of the circle with a radius of " << a << " is " << c << " \n";
          cout << "\n";
          cout << "\n";
          cout << "Would you like to do this again?? \n";
          cout << "Type 1 to continue, or any other key to exit.. \n";
          cin >> looping;

          if ( looping != 1 )
                looping = 2;

     }while ( looping == 1 );

cout << "\n";
cout << "Thanks for using my Area of a Circle program !! \n";
cout << "Good Bye !!\n";
cout << "******************************************** \n";
cout << "******************************************** \n";
cout << "\n";
cout << "\n";

return 0;
}

I just added the line :

 if ( looping != 1 )
looping = 2;

Now it exits gracefully if a letter or other key is hit instead of the 1 key.

[MrFreeze]

you should check the return code of every cin >>x;

http://www.arachnoid.com/cpptutor/student1.html

MrFreeze