Solved

C++ class template problem

Posted on 2010-11-13
3
348 Views
Last Modified: 2012-05-10
I am experimenting with templates in C++ using Borland C++ Builder.
I have used STL quite successfully in the past and I have encountered a problem in using a simple class template that I have written myself.

The code snipplet shows my header file and the cpp file.
The compile-time error occurs when compiling the header file with the following error message:

[C++ Error] Unit1.h(25): E2293 ) expected
 

The error refers to the line of code where the x member is declared in the Form1 class.

If I move the declaration of x from the Form1 header to the initialisation code in the constructor for Form1 however, no error is reported. (As per the code that is shown that is commented out).

Is is possible to declare a variable x of type Vtor<int> in the header of Form1 with a size of 5 ?



// header file Unit1.h

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>

template <class T> class Vtor
{
   T *data;
   int size;
public:
   Vtor(int);
   ~Vtor( ) { delete[ ] data; }
   T& operator[ ] (int i) { return data[i]; }
};
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:	// IDE-managed Components
private:	// User declarations
   Vtor<int> x(5);   // Generate a vtor to store five integers

public:		// User declarations
    __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

// cpp file Unit1.cpp
#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;

template <class T> Vtor<T>::Vtor(int n)
{
   data = new T[n];
   size = n;
};

//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
//  Vtor<int> x(5);
  for (int i = 0; i < 5; ++i)
      x[i] = i;              //  Initialize the vector.
}
//---------------------------------------------------------------------------

Open in new window

0
Comment
Question by:alcindor
  • 2
3 Comments
 
LVL 53

Accepted Solution

by:
Infinity08 earned 500 total points
ID: 34127627
You can't initialize the data member there.

I assume you meant something like this (left out irrelevant stuff) :
class TForm1 : public TForm
{
private:
   Vtor<int> x;                      // <--- definition

public:
    TForm1() : x(5) { }              // <--- initialization via constructor
};

Open in new window

0
 
LVL 2

Author Closing Comment

by:alcindor
ID: 34150966
I have already accepted this solution. There is a fault on your web application ?
0
 
LVL 53

Expert Comment

by:Infinity08
ID: 34152726
It looks like it worked now. If you think there is a bug or other issue with the web site, you can report that by posting a question in the EE bugs zone (or the general Community Support zone).
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article will show you some of the more useful Standard Template Library (STL) algorithms through the use of working examples.  You will learn about how these algorithms fit into the STL architecture, how they work with STL containers, and why t…
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.

831 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question