Chapter 7 Friends, page 196

phztfte1 · April 16th, 2016, 10:26 AM

To make a specific member function of the Spreadsheet class a friend, the following statement was added to the SpreadsheetCell class:

Code:

friend void Spreadsheet::setCellAt(int x, int y, const SpreadSheetCell$ cell);

However, when doing so, there is a red squiggly line under Spreadsheet. Why so? Is it because Spreadsheet and SpreadsheetCell are not in the same namespace?

Marc Gregoire · April 17th, 2016, 01:46 PM

In my Visual Studio (2015, Update 1), I don't see a red squiggle.
Note however that you have a small typo in your line. The correct line is:

Code:

friend void Spreadsheet::setCellAt(int x, int y, const SpreadsheetCell& cell);

phztfte1 · April 17th, 2016, 06:53 PM

Marc,

It appears that I made the typo when posting the code. The error message I get now is as follows:

Code:

1>  SpreadSheet.cpp
1>f:\professional c++\chapter 6\spreadsheet\spreadsheet\spreadsheetcell.h(10): error C2653: 'SpreadSheet' : is not a class or namespace name
1>  Generating Code...
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Here is the SpreadSheetCell.h file:

Code:

// SpreadSheetCell.h;

#include <string>
using std::string;

	class SpreadSheetCell
	{
	public:
		friend bool checkSpreadSheetCell(const SpreadSheetCell& cell);
		friend void SpreadSheet::setCellAt(int x, int y, const SpreadSheetCell& cell);
		SpreadSheetCell();										// default operator																				// default constructor
		SpreadSheetCell(double initialValue);					// single-argument constructor for double										// one argument constructor
		SpreadSheetCell(const string& initialValue);			// single-argument constructor for string
		SpreadSheetCell(const SpreadSheetCell& src);			// copy constructor
		SpreadSheetCell& SpreadSheetCell::operator= (const SpreadSheetCell& rhs);
		void setValue(double inValue);
		double getValue() const;
		void setString(const string& inString);
		string getString() const;
		typedef enum { Red = 1, Green, Blue, Yellow } Colors;
		void setColor(Colors color);

	protected:
		static string doubleToString(double inValue);
		static double stringToDouble(const string& inString);
		double mValue;
		string mString;
		mutable int mNumAccesses = 0;
		Colors mColor = Red;
	};

I made no changes to the SpreadSheetCell.cpp file because the method is defined in the SpreadSheet.cpp file.

Marc Gregoire · April 18th, 2016, 02:13 PM

You are missing a:

Code:

#include "Spreadsheet.h"

or a forward declaration of Spreadsheet.

phztfte1 · April 18th, 2016, 10:15 PM

Marc,

When the statement

Code:

#include "Spreadsheet.h"

is added, a red squiggly line appears under #include with the error message: "Error: #include file "f:\professional c++\...\SpreadSheet.h" includes itself.

When I build a solution, the following error message is displayed:

Code:

1>------ Build started: Project: SpreadSheet, Configuration: Debug Win32 ------
1>  SpreadSheetCell.cpp
1>f:\professional c++\chapter 6\spreadsheet\spreadsheet\spreadsheet.h(3): fatal error C1014: too many include files : depth = 1024
1>  SpreadSheet.cpp
1>f:\professional c++\chapter 6\spreadsheet\spreadsheet\spreadsheetcell.h(3): fatal error C1014: too many include files : depth = 1024
1>  Generating Code...
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

I suspect this error message is because of the SpreadSheet.h file which contains the statement

Code:

#include "SpreadSheetCell.h"

. See below.

Code:

// SpreadSheet.h

#include "SpreadSheetCell.h"

	class SpreadSheetApplication;		// forward declaration
	class SpreadSheet
	{
	public:
		SpreadSheet(int inWidth, int inHeight, SpreadSheetApplication& theApp);			// three-argument constructor
		SpreadSheet(const SpreadSheet& src);				// deep copy constructor
		SpreadSheet& operator= (const SpreadSheet& rhs);	// assignment operator
		void copyFrom(const SpreadSheet& src);			// helper method
		~SpreadSheet();										// destructor
		void setCellAt(int x, int y, const SpreadSheetCell& cell);
		SpreadSheetCell getCellAt(int x, int y);
		int getId() const;
		static const int kMaxHeight = 100;
		static const int kMaxWidth = 100;

	protected:
		static int sCounter;
		int mId;
		bool inRange(int val, int upper);	// protected helper method
		int mWidth, mHeight;		// data members
		SpreadSheetCell** mCells;	// SpreadSheetCell** used instead of a two-dimensional array 
		// to accommodate varying cell height and width
		SpreadSheetApplication& mTheApp;
	};

If I remove the

Code:

#include "SpreadSheetCell.h"

, red squiggly lines appear wherever "SpreadSheetCell" is stated.

What's going on?

Marc Gregoire · April 20th, 2016, 03:36 PM

Then you can probably use a forward declaration of Spreadsheet in SpreadSheetCell.h.

It's hard to follow what exactly you are trying to do.
Why don't you download the source code for the book from the Wiley/Wrox website?
All source code from the book is available for download and all that code is compilable without any changes.

phztfte1 · April 20th, 2016, 11:20 PM

Marc,

There was a beginning C++ book I read that said you could download the code or you could type in the code. If you type in the code, you will learn more because of the errors you will make. Resolving those errors will help you when you actually code a program.

I do peek at the downloaded source code to see if I am on track. There were a few differences. However, if I just change my code to be the same as the downloaded code without knowing why, I am not learning.

If I recall correctly, the book does not say what header files to incorporate into the ".cpp" file. You sort of have to figure it our.

What I am trying to do is find errors early. So, I compile the code at certain points, and if successful, the program is okay except for logical errors.

Since the code did not compile, I know something is wrong, but have yet to figure it out. That is why I am asking for help.

What is a forward declaration of SpreadSheet?

Marc Gregoire · April 21st, 2016, 01:26 PM

That is correct. That way you learn more. I just wanted to make sure you knew that you can download the source code for this book and look at it.

Forward declarations are briefly discussed and demonstrated in Chapter 7 on page 184 (second edition of the book) section "Reference Data Members".

phztfte1 · April 21st, 2016, 10:26 PM

Marc,

I found the solution. I added the preprocessor directives for each header file although it is only required for the SpreadsheetCell.h file.

Code:

#ifndef _XXXXXX_XXX_H_
#define _XXXXXX_XXX_H_
...
#endif

The code compiles.

Marc Gregoire · April 26th, 2016, 02:02 PM

Glad you found the solution.
Well done :)