Thread: Probelm when entering a string

  1. #1
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    Probelm when entering a string

    I've got a bit of code working so it will accept the number you put it and use it else where (no need to show you this), but if a string/letter is entered then the program crashes. I'd like it to come up with an error if a string is entered.

    Not an essential part of code for the program, but i'd like to get it as bug free as possible, and I cant seem to find how to fix this anywhere.

    Code:
     
    valid = 0;
    
      do
      {
    	  cout << "\n  enter the number of songs you wish to enter: ";
    	cin >> songs;
    	if (number < 1 || number > 100)
    	{
    		cout << "\n  enter again between 1 and 100";
    	}
    	else
    	{
    		valid++;
    	}
      }while (valid < 1);
    Anyone help?

    Thanks in advance.

  2. #2
    Its hard... But im here swgh's Avatar
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    > valid = 0;

    is that global? If so, in your loop use ::valid++
    It makes it clearer, if it really is a global variable that is, hard to
    tell as the indentaton is off a bit,

    If you want to test if a stirng is entered, then create a sperate condition in the
    do-while loop that tests this issue. You could use a char[] for this
    Double Helix STL

  3. #3
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    To handle bad input, you just need to check the return value of the cin >> operation. A common way to do it is like this:
    Code:
    while (!(cin >> songs))
    {
      cin.clear();
      cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
      // error message and re-prompt
    }
    You should #include <limits> for numeric_limits and <ios> for streamsize. That line makes sure all of the bad input is ignored.

  4. #4
    Hurry Slowly vart's Avatar
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    cin >> songs;
    if (number < 1 || number > 100)

    You change the variable songs and check the value of number. Seems strange to me
    All problems in computer science can be solved by another level of indirection,
    except for the problem of too many layers of indirection.
    David J. Wheeler

  5. #5
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    Quote Originally Posted by vart
    cin >> songs;
    if (number < 1 || number > 100)

    You change the variable songs and check the value of number. Seems strange to me
    Yeah it is actually that, just a typo.

    Thanks guys got it working now.

    Cheers!

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