Working on a calculator mimicker.

[jackelinblack]

My problem is that I can't get the loop to exit so that I can exit out of the program without actually have to press the "x" button.

#include <iostream>
using namespace std;

int main()
{
	float x,y;
	char math,exit;

do
	{
	
cout<<"Please enter number"<<endl;
cin>>x;
cout<<"Enter mathamatical operator"<<endl;
cin>>math;
cout<<"Enter another number"<<endl;
cin>>y;

		

switch(math)
{
case '+':
	cout<<x<<" "<<math<<" "<<y<<" = "<<x+y<<endl;
break;

case '-':
	cout<<x<<" "<<math<<" "<<y<<" = "<<x-y<<endl;
break;

case '*':
	cout<<x<<" "<<math<<" "<<y<<" = "<<x*y<<endl;
break;

case '/':
	cout<<x<<" "<<math<<" "<<y<<" = "<<x/y<<endl;
	if (y==0){
		cout<<"Undefined"<<endl;}
break;
}
cout<<"type y to quit"<<endl;
cin>>exit;
cout<<endl;
}while(exit=='Y' || 'y');

system("pause");

return 0;
}

[jwkNwA7f]

On line 44, it says to keep looping only while exit is equal to y. It should be:
} while (exit != 'Y' || exit != 'y')

[jackelinblack]

I originally had it like that, it just continued looping. Tried it again just to make sure and I can verify that it just keeps looping.

[cire]

It should be:

while (exit != 'Y' && exit != 'y' )

Note that the original code:

while ( exit == 'Y' || 'y' ) will always evaluate to true because it is equivalent to:
while ( (exit == 'Y') || 'y' ) and since 'y' is non-zero, 'y' evaluates to true.

In the line provided by retsgorf297, while ( exit != 'Y' || exit != 'y' ),
we can take a look at the expression when exit is 'Y' to see why it doesn't work:

while ( 'Y' != 'Y' || 'Y' != 'y' )

which is equivalent to:

while ( false || true )

which simplifies to:

while (true)

[jackelinblack]

Thank you very much cire, it worked but i'm a little confused.

I originally had while ( exit != 'Y' || exit != 'y' )
why won't making the statement true exit the loop?

From what i was understanding i thought the statement would read while exit is not Y or y continue (false), but if it is Y or y (true) exit.

[cire]

why won't making the statement true exit the loop?

Loops stop iterating when the loop condition is false.

[jackelinblack]

Oh thank you very much.