Bool function `again()` getting same result

Question

I wrote a bool function again() to prompt the user to re-run the program, but for whatever answer the user enters the program will re-run no matter what.

bool again()
{
  //Local variable                                                                                                                        
  char answer;

  cout<<"Would you like to re-run? (Y/N) ";
  cin>>answer;
  cin.ignore(100,'\n');


  if(answer == 'Y' || 'y')
  {
    return true;
  }

  if(answer == 'N'  || 'n')
  {
     return false;
  }
}

...

  do
       {
         menu(gameamount,response);

         if (response == 1)
         {
           inputs(gameamount, game_count);
           writeout(gameamount);
         }
         if (response == 2)
         {
           outputs(gameamount, game_count);
         }
       }while(again());

       return 0;
}

I tried using else and else if and returning false after the first if-statement but that still did not work, I can't put the block of code in main to conserve space so I have to create a boolean function to ask the user to re-run the program.

Answer 1

There's a logic error in your code.

Try this:

if(answer == 'Y' || answer == 'y')
{
    return true;
}

if(answer == 'N'  || answer == 'n')
{
    return false;
}

You should also possibly output a message in case the user decides to type something other than 'Y','y','N' or 'n'.

Also, I'm not 100% sure about this, but I think that your code is always returning true in the first if statement because you are checking to see if 'y' is true, which I think it always is.

if(answer == 'Y' || 'y')
{
    return true;
}

Any value other than 0 would equate to true, and the character 'y' when treated as an integer is equal to it's corresponding ASCII code (121 in this case).

Answer 2

Try to replace the line

if(answer == 'Y' || 'y')

by

if(answer == 'Y' || answer == 'y')

Answer 3

The line

if (answer == 'Y' || 'y')

will enter the if block in every case, since it won't evaluate to what you intended. It evaluates answer == 'Y' which is true or false, but then ORs this value with 'y'. In this step, 'y' is converted to a boolean value in order to be ORed logically, and since all numbers unequal to 0 are converted to true the whole expression is always true.

If you correct this to

if (answer == 'Y' || answer == 'y')

you still have the following problem:

Your function only returns a value in the case where the user enters either a Y or an N in lower or upper case. But what if the user enters an invalid letter? You need to define a behavior for this situation. Currently your program doesn't have a return statement for this case, resulting in undefined behavior, which means the result of the function can be anything.

You can either return a default value (e.g. false), then you need to remove the second conditional if but keep the return false.

Another solution is to loop until the user entered a valid value.