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c++ help!

Discussion in 'Mac Programming' started by mmmdreg, Mar 19, 2005.

  1. macrumors 65816


    Hey this is really basic and I don't see why I can't do it but hey. I want something that will read in input until a blank line is entered (ie return is pressed twice).
    	string inputText = "";
    	int finish = 0;
    	char tempInput;
        cout << "Type the text. To end, type a blank line.\n";
    	while (finish < 2) {
    		tempInput = getchar();
    		if (tempInput != '\n') {
    			finish = 0;
    			inputText = inputText + tempInput;
    		else //if (tempInput == '\n')
    The idea is that if there is one blank line, "finish" is incremented. If another, it goes to 2 and the while loop ends. If anything else is entered, it should reset to 0.

    Initially, I was trying to use getline but I don't think you can use two characters as thing that terminates it (ie getline(a, b, "2x \n in here)). Apart from that, it worked perfectly.

    So any help would be appreciated.
  2. macrumors 65816


    I would guess that there is a hidden character that you aren't expecting being inserted before the '\n' character. If I remember correctly, it's probably the line feed character. To do text input, I'd recommend using cin anyway. You're already using cout, why not stick to C++ streams. ;)

    Make sure to declare enough memory for your input as well. As defined, you're only allowing 1 character. You code above could actually go out of bounds pretty easily.
  3. macrumors 65816


    I thought you can't input a whole lot of stuff using cin.. I've only been doing this for a bit so correct me if I'm wrong.
  4. macrumors 603


    try this

    if (tempInput != '\n' && tempInput != '\r') {
    } else if (tempInput == '\n') {

    Return sometimes triggers two characters \r\n or \n\r depending on platform.

    You can use cin to read a lot of stuff including strings and numbers, but cin will just skip whitespace ( \n\r\f\t) so it will not be possible to detect a double return using cin.

    I don't think the code will go out of bounds because it uses the string class, but I haven't really used the string class, so I'm not 100% sure.
  5. macrumors 65816


    thanks for your idea. Unfortunately it didn't work =(
    I don't know how to debug properly but from test cout things, it seems that the program keeps going through "finish = 0" and so well keep on looping..even when using both \n and \r..

    I tried using getline just then, and the result was the same as the above example with the "finish = 0" commented out. Pretty much, it works if two newlines are inputted together in the first instance of a newline.. but it doesn't work if i type something, newline, type something, then do two newlines..

    this works:
    blah blah blah

    but this doesn't:
    blah blah blah
  6. macrumors 65816


    The problem turns out to be an xcode bug. Compiling and running the executable from terminal.app makes it run fine.

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