cout formatting

This is a discussion on cout formatting within the C++ Programming forums, part of the General Programming Boards category; Trying to some simple column formatting..... Basically producing a table, where the headers display the name of the values stored ...

  1. #1
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    cout formatting

    Trying to some simple column formatting.....

    Basically producing a table, where the headers display the name of the values stored in the tables.

    i.e. file << "KT"<< "\t" << "A" << "\t" << "E" << "\t" << "A_Norm" << "\t" << "E_Norm" << "\t" << "A/(KT)*2".... etc etc

    then underneath the values

    KT << "\t" << A << "\t" << B << "\t" << C << "\t" << D << "\t" << E << "\t" << F << "\t" << G << "\t" << H << "\t" << I << endl

    However these columns dont seem to align. How can I force alignment...or set-up in nice neat columns?

  2. #2
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    i.e.

    Name Name2 Name3
    Value Value2 Value3

  3. #3
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    You can use "setwidth()" to set the width of each element you output.

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  4. #4
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    I have tried the following:

    cout << "G. " << setw(8) << 34 << setw(8) << 45 << endl;

    after including

    #include <iomanip>

    as well, but no avail, I get the following on compile:

    error: ‘setw’ was not declared in this scope

  5. #5
    Cat without Hat CornedBee's Avatar
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    setw() is in namespace std.
    All the buzzt!
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  6. #6
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    ok but it still does not work!

    I am running with GNU c++ compiler.

  7. #7
    C++ Witch laserlight's Avatar
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    What code did you test with?
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  8. #8
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    Can you show the code that "doesn't work", and also describe how it doesn't work?

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  9. #9
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    >ok but it still does not work!
    The default is right justification, so you might try left justification.
    Code:
    cout << std::left << "G. " << setw(8) << 34 << setw(8) << 45 << endl;

  10. #10
    Frequently Quite Prolix dwks's Avatar
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    Things that you should do:
    • Use either std::setw() or a using statement such as
      Code:
      using namespace std;
      or
      Code:
      using std::setw;
      This goes for everything, including cout and left and endl.
    • Call setw() before you print your data, like this.
      Code:
      std::cout << std::setw(10) << string << std::endl;
      If you call it afterwards, it will have no effect.


    Code:
    cout << std::left << "G. " << setw(8) << 34 << setw(8) << 45 << endl;
    Using std::left but not std::cout and std::setw and std::endl implies that the code used something like
    Code:
    using std::cout;
    using std::endl;
    using std::setw;
    // but not
    // using std::left;
    I think either
    1. the programmer won't care about namespaces, and just grab the whole thing with using namespace std; or
    2. the programmer will care enough about namespaces to put std:: in front of everything or use a using directive for each identifier.

    Besides which, it's inconsistent. And unimportant . . . .
    Last edited by dwks; 01-09-2008 at 02:31 PM.
    dwk

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  11. #11
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    Quote Originally Posted by dwks View Post
    Using std::left but not std::cout and std::setw and std::endl implies that the code used something like
    Agreed. I put std:: in there as an extra precaution, and to make left stand out, since the OP was having some issues with the compiler recognizing setw(), and it being good practice in larger programs.

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