Formatting output

This is a discussion on Formatting output within the C++ Programming forums, part of the General Programming Boards category; My code is working perfectly, except for one thing. I need to display my output in the following format: 1 ...

  1. #1
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    Formatting output

    My code is working perfectly, except for one thing. I need to display my output in the following format:

    1 2 3 4 5
    6 7 8 9 10
    11 12 13 14 15
    16 17 18 19 20

    (no more than 5 numbers per line)

    What I'm getting is this:

    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

    My instructor told me to use mods, but we never went over that in class, and I can't find it in the book. Any help would be very much appreciated.

  2. #2
    and the hat of wrongness Salem's Avatar
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    Look up the % operator then
    mods being modulo
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  3. #3
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    Thanks for the tip.

  4. #4
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    OK, only thing I can find on the % is using it for dividing numbers. There's nothing in the book about using it for displaying output. Anyone got any ideas?

  5. #5
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    Run this and you'll see what Salem meant by using modulo to help with formatting output.
    Code:
    #include <iostream>
    
    using namespace std;
    
    int main()
    {
      for (int i = 1; i <= 20; i++) {
        cout << i;
        if (i % 5 == 0) {
          cout << '\n';
        }
        else {
          cout << ' ';
        }
      }
    }

  6. #6
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    Thanks for the help.

  7. #7
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    Thanks. I ended up doing it like this and it works fine. Thanks again for the help.

    Code:
    for(numbers = 0; numbers < maxlist; numbers++)
        {
           infile>>list[numbers];
           if((numbers + 1) % 5 == 0)
           {
              outfile<<list[numbers]<<" "<<endl;
              cout<<list[numbers]<<" "<<endl;
           }
           else
           {
              outfile<<list[numbers]<<" ";
              cout<<list[numbers]<<" ";
           }
        }
    I did it that way in case, in the future, someone wanted to change the display to 6 per line, all they'd have to do is change every instance of 5 to 6.

  8. #8
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    I did it that way in case, in the future, someone wanted to change the display to 6 per line, all they'd have to do is change every instance of 5 to 6.
    This sounds like a good place to use a constant.
    Code:
    const int ITEMS_PER_LINE = 5;
    
    [...]
    
    for(numbers = 0; numbers < maxlist; numbers++)
    {
      infile>>list[numbers];
      if((numbers + 1) % ITEMS_PER_LINE == 0)
      {
        outfile<<list[numbers]<<" "<<endl;
        cout<<list[numbers]<<" "<<endl;
      }
      else
      {
        outfile<<list[numbers]<<" ";
        cout<<list[numbers]<<" ";
      }
    }
    Now if you want to change the display to 6 per line, you only have to make one change, regardless of how many times you write the display loop.

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