Annoying problem...

It's just a little nooby problem. In my book it said to try and design a program that would take two numbers and add or subtract them (With input from the user). Anyway this is what I tried to do:

Code:

void main()
{
	int no1, no2;
	char plusminus;
	
	cout << "\n- Please enter 2 integers to be added or subtracted -";
	cout << "\n\nNumber 1: ";
	cin >> no1;
	
	while(plusminus != '+' || plusminus != '-')
		{
			cout << "\n\nWould you like to add or subtract? (+/-): ";
			cin >> plusminus;
		
			switch(plusminus)
			{
				case '+':
					plusminus = '+';
				break;
				case '-':
					plusminus = '-';
				break;
				default:
					cout << "\n\nERROR: That is not an option.\n";
			}
		}
	
	cout << "\n\nNumber 2: ";
	cin >> no2;
	
	if(plusminus == '-')
		cout << endl << no1 << " " << plusminus << " " << no2 << " = " << no1 - no2;
	else
		cout << endl << no1 << " " << plusminus << " " << no2 << " = " << no1 + no2;
}

The problem is when you try and select whether it's plus or minus it just loops even if you select + or -...

Thanks very much if you can help.

-Marlon

Code:

while(plusminus != '+' || plusminus != '-')

should be

Code:

while(plusminus != '+' && plusminus != '-')

In your version it would have to be a + and a - at the same time to skip the loop
Kurt

Heres another solution using if else instead of the while loop to avoid the confusion.

Code:

int main()
{
    using namespace std;
    
	int no1, no2;
	char plusminus;
	
	cout << "\n- Please enter 2 integers to be added or subtracted -";
	cout << "\n\nNumber 1: ";
	cin >> no1;
	cout << "\n\nWould you like to add or subtract? (+/-): ";
	cin >> plusminus;
	cout << "\n\nNumber 2: ";
	cin >> no2;
	
	if(plusminus == '+')
	             cout<<no1+no2;
              
              else
              if(plusminus == '-'){
                           cout<<no1+no2;
                           }                           
                           else
                           cout<<"Input error";
                       
                                                
              return 0;

}

Also make sure you initialize your variables before you use them. In this case, you use plusminus before it is initialized. Set it to any character you want other than '+' or '-' so that the loop will be entered the first time.

Thank you all very much for your help!

ZuK:

Your solution worked (Thank your very much ). But the reason I did the '||' instead of the '&&' is because I read in the book that '&&' would mean 'and'.

It says if(A&&B) means If A and B are true.

It also says if(A||B) means If A or B are true.

Is it a mistake or am I looking at that sentence from a strange view. Thanks anyway though

Jreak:

I always seem to do things the hard way I knew there had to be a simpler solution... Thank you very much for showing it to me

Daved:

Thank you for the advice, I'll try to do that from now on

Originally Posted by StickyGoo

Is it a mistake or am I looking at that sentence from a strange view. Thanks anyway though

Yes you do but it is a very common mistake if you use negations.
mybe an easier to read solution would be

Code:

while( ! (plusminus== '+' || plusminus == '-'))

Kurt

Originally Posted by ZuK

Code:

while( ! (plusminus== '+' || plusminus == '-'))

So does that mean....

While Plusminus is not equal to '+' And It's also not equal to '-' Then....

Yes it does. Both of my versions do.

Code:

( not A ) and ( not B )

is the same as

Code:

not ( A or B )

Kurt

Brilliant. Thank you very much for your help, I really appreciate it.

Have a good easter too!