Can't understand errors about class & List objects

Programming
,
1

I am having trouble understanding the error messages I am receiving when declaring a TObjectList and a Chord object in my VCL application for Windows.

I have declared TObjectList<Chord> chordList and Chord chordObj both inside and outside of the TForm1 class. Each way generates different error messages.

I have included my header and cpp files below.

Header File:

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <System.Contnrs.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
#include <string>

//---------------------------------------------------------------------------

typedef std::string string;

class Chord {
private:
protected:
public:
    string searchKey;
    string cKey;
    string cRank;
    int    cFret;
    string cPos;
    string cPlay;

    Chord() {}
    Chord(string ck,string cr,int cf,string cp,string csp) {
        cKey=ck;
        cRank=cr;
        cFret=cf;
        cPos=cp;
        cPlay=csp;
    }
};

TObjectList<Chord> chordList;
Chord chordObj;

//---------------------------------------------------------------------------

class TForm1 : public TForm
{
__published:    // IDE-managed Components
private:    // User declarations
public:     // User declarations

    __fastcall TForm1(TComponent* Owner);

};

//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

CPP File:

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------

I am trying to declare a TObjectList and a Chord object in my VCL application for Windows, but I am receiving the following error messages:

[bcc32c Error] Unit1.h(38): expected unqualified-id
[bcc32c Error] Unit1.h(39): must use 'class' tag to refer to type 'Chord' in this scope
  wingdi.h(3740): class 'Chord' is hidden by a non-type declaration of 'Chord' here

Should I be using TList versus TObjectList, or some other version of a List object, given there will be hundreds of Chord objects in the list? What is the best way of declaring TObjectList and Chord in this scenario?

2

The issue you are facing is related to the declaration of TObjectList<Chord> chordList and Chord chordObj in the header file.

To resolve the error messages, you should move the declaration of TObjectList<Chord> chordList and Chord chordObj inside the TForm1 class declaration in the header file.

Here is the updated header file:

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <System.Contnrs.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
#include <string>

//---------------------------------------------------------------------------

typedef std::string string;

class Chord {
private:
protected:
public:
    string searchKey;
    string cKey;
    string cRank;
    int    cFret;
    string cPos;
    string cPlay;

    Chord() {}
    Chord(string ck,string cr,int cf,string cp,string csp) {
        cKey=ck;
        cRank=cr;
        cFret=cf;
        cPos=cp;
        cPlay=csp;
    }
};

//---------------------------------------------------------------------------

class TForm1 : public TForm
{
__published:    // IDE-managed Components
private:    // User declarations
    TObjectList<Chord> chordList;
    Chord chordObj;
public:     // User declarations
    __fastcall TForm1(TComponent* Owner);

};

//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

By moving the declarations inside the class, you ensure that they are in the correct scope and can be properly recognized by the compiler.