using for loops to display a parallelogram

This is a discussion on using for loops to display a parallelogram within the C++ Programming forums, part of the General Programming Boards category; our output should look like this (the underscores are just there to make it display properly): This program will output ...

  1. #1
    Registered User helloalyssa's Avatar
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    using for loops to display a parallelogram

    our output should look like this (the underscores are just there to make it display properly):

    This program will output a parallelogram.
    How long do you want each side to be? 9
    Please enter the character you want it to be made of: *
    *
    **
    ***
    ****
    *****
    ******
    *******
    ********
    *********
    _********
    __*******
    ___******
    ____*****
    _____****
    ______***
    _______**
    ________*



    i'm almost done but i'm having a problem with getting the bottom half to indent properly. here is the code i have for it:

    Code:
    for (int row = length - 1; row >= 1; row--)
    
      {
    
        for (int col = 1; col <= row; col++)
    
        {
    
          cout << setw(1 + length - row) << displayChar;
    
        } 
    
        cout << "\n";
    
      }
    i tried putting in length and row for setw but they shift too far to the right. the equation that's in there now is something a tutor suggested to me but it's not working either. could anyone help me? thanks!

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    One debugging technique is to try outputting the value of the equation to see if it's giving the number you expect. If it isn't, adjust the equation until it does, and then hopefully you will also get proper output. If it is giving you the number you expect, then maybe setw isn't working as you expect or there is some other problem.

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    Registered User helloalyssa's Avatar
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    i don't think there is another problem besides setw. it complies correctly and displays the right amount of characters but the spacing is off. it's definitely setw not working as i thought it would but after checking the forums for this problem for my online class, everyone seems to be encountering the same problem.

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    Is this how the parallelogram is supposed to look (with a length of 4):
    Code:
    *
    **
    ***
    ****
     ***
      **
       *
    ?

    If that's the case, then your code itself is the problem. I would start with the first part where you are outputting characters with no spaces before them (or between them). See if you can get that working first. You shouldn't need setw for that at all.

    Once you have that working, see if you can get the second half where there are spaces in front. Think about what setw does and when you're supposed to call it. A good trick is to just follow the code step by step with a pencil and paper and watch what it does (a debugger is actually better if you know how to use yours).

  5. #5
    Registered User helloalyssa's Avatar
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    yeah it's supposed to look like that. the code i have posted is for the second half of the triangle. my teacher told us to make the code like that; code the first half then the second half.

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    Ok, that's good. That makes sense. Now you just have to think about what setw is supposed to do, and what it does where you're calling it. Step through the loops with an example value and see what it is doing. Or add debugging code, something like this just before the line that calls it:
    Code:
    cout << "{calling setw with value: " << 1 + length - row << "}";
    Hopefully that will give you a clue as to what is going wrong here (it's actually just a small mistake).

  7. #7
    Registered User helloalyssa's Avatar
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    thank you! i figured it out with the help of you and the local lab tutor. heh. all i had to was nest an if loop into the nested for loop.

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    Cool. I fixed it a different way (moving the setw outside of the inner loop), but if it works, great.

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