errors with class constructor

This is a discussion on errors with class constructor within the C++ Programming forums, part of the General Programming Boards category; I'm experimenting with classes(for the first time) where basically you create a box with a name, you can move it ...

  1. #1
    30 Helens Agree neandrake's Avatar
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    errors with class constructor

    I'm experimenting with classes(for the first time) where basically you create a box with a name, you can move it and close/open it, etc., very simple. However, I get an error when compiling, it says that the constructor is not allowed a return type. What exactly is the error?

    Code:
    BOX::BOX() {
    	xpos=0;
    	ypos=0;
    	open=false;
    }
    What is the return type that it's talking about?

  2. #2
    _B-L-U-E_ Betazep's Avatar
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    where is your declaration? You implementation doesn't have a return type it seems...
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  3. #3
    30 Helens Agree neandrake's Avatar
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    whoops, i also forgot to mention that I'm using Microsoft Visual C++ 6, f.y.i.

    here's the declaration:
    Code:
    class BOX
    {
    public:
    	BOX();
    	~BOX();
    	bool open;
    	int xpos,ypos;
    	char name[31];
    	void openbox();
    	void closebox();
    	void push();
    	void pull();
    	void move(long direction);
    }
    Environment: OS X, GCC / G++
    Codes: Java, C#, C/C++
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  4. #4
    _B-L-U-E_ Betazep's Avatar
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    on a hunch... try

    open = 0;
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  5. #5
    30 Helens Agree neandrake's Avatar
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    that wasn't the problem, same error. for the hell of it, here's the deconstructor, it's the same damn thing, but it doesn't have any errors:

    Code:
    BOX::~BOX {
    	xpos=0;
    	ypos=0;
    	open=false;
    }
    [EDIT] No ****, just realized the problem. I have to get rid of the () in the constructor.[/EDIT]
    Environment: OS X, GCC / G++
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  6. #6
    _B-L-U-E_ Betazep's Avatar
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    Yeah... I was confused... it compiled fine for me.
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  7. #7
    30 Helens Agree neandrake's Avatar
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    were you compiling with or without the ()?
    maybe it's a setting in my compiler. because now I get another longer error. It says

    C:\PROGRAM FILES\MICROSOFT VISUAL STUDIO\MyProjects\type_msg\main.cpp(22) : fatal error C1001: INTERNAL COMPILER ERROR
    (compiler file 'msc1.cpp', line 1786)
    Please choose the Technical Support command on the Visual C++
    Help menu, or open the Technical Support help file for more information
    Error executing cl.exe.
    I have MSDN installed and it couldn't load the specific help page because I need disc 2 (don't have it where i am).

    this is most likely an enviornment configuration that's giving me errors?
    Environment: OS X, GCC / G++
    Codes: Java, C#, C/C++
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  8. #8
    _B-L-U-E_ Betazep's Avatar
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    with... but I let the compiler put in the default destructor as you were not allocating any memory.
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  9. #9
    30 Helens Agree neandrake's Avatar
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    what do you mean with the default deconstructor? Would doing what you do with it make the constructor work?
    Environment: OS X, GCC / G++
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  10. #10
    _B-L-U-E_ Betazep's Avatar
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    this is the code I compiled into an object file...

    Code:
    in file.h
    ++++++++++++++++++++++
    
    class BOX
    {
      public:
    
          BOX();
    
          int xpos, ypos;
          bool open;
    
          // note:  it is a good idea to make your variables private
    };
    
    // i didn't include macro guards... as I was just testing your situation
    ++++++++++++++++++++++
    
    in file.cpp
    ++++++++++++++++++++++
    #include "file.h"
    
    BOX::BOX()
    {
       xpos=0;
       ypos=0;
       open=false;
    }
    +++++++++++++++++++++++
    that compiled fine for me...

    If you do not explicitly define a constructor/destructor, the compiler puts in a generic one for you. I usually don't do a destuctor unless I allocate memory with 'new'... which I 'delete' in the destructor....

    that is pretty much it.... I do not know what is up with your compiler...
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  11. #11
    30 Helens Agree neandrake's Avatar
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    oh well, i'm about to give up for today, I've included the file if you want to take a look. Anyways, what are macro guards?
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    Environment: OS X, GCC / G++
    Codes: Java, C#, C/C++
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  12. #12
    _B-L-U-E_ Betazep's Avatar
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    Code:
    ...put void in front of all of these...
    
    BOX::closebox() {
    	open=false;
    }
    BOX::openbox() {
    	open=true;
    }
    BOX::push() {
    	xpos++;
    }
    BOX::pull() {
    	xpos--;
    }
    BOX::move(long direction) {
    	if (direction==RIGHT)
    		ypos++;
    	if (direction==LEFT)
    		ypos--;
    
    ...put the parens back in these...
    
    BOX::BOX (){
    	xpos=0;
    	ypos=0;
    	open=false;
    }
    BOX::~BOX (){
    	xpos=0;
    	ypos=0;
    	open=false;
    }
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  13. #13
    _B-L-U-E_ Betazep's Avatar
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    when all else fails... try simplicity to determine your problem.

    Write a simple class that does nothing and compile it. Find out what your errors are from there, and then see if you can find those errors in your bigger problem.

    Code:
    class test
    {
       public:
           test();
           int a;
    };
    
    test::test()
    {
       a = 0;
    }
    
    int main()
    {
       test it;
       
       return 0;
    }
    think about it
    Last edited by Betazep; 03-17-2002 at 12:39 AM.
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  14. #14
    30 Helens Agree neandrake's Avatar
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    ok, i did what you said, however, if I put the parenthesis back in the deconstructor, i get 19 errors. if i put them in the constructor(and not in the deconstr.) I get an error about how it can't have a return type. I have the voids like:

    Code:
    void BOX::move(long direction) {
    	if (direction==RIGHT)
    		ypos++;
    	if (direction==LEFT)
    		ypos--;
    }
    and it didn't seem to do much. gar! (that's not directed at you.)
    Last edited by neandrake; 03-16-2002 at 07:25 PM.
    Environment: OS X, GCC / G++
    Codes: Java, C#, C/C++
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  15. #15
    _B-L-U-E_ Betazep's Avatar
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    then compile the code I gave above...
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