Programming Forums > Application Development > C++

-=PARADOX=- · Nov 24th, 2005, 9:59 AM

Hi there again

I have one annoying problem here :eek:

I have one class 'CVector':

class CVector
{
        int *vector;
        unsigned n;   // this is the number of elements
public:
        CVector( );
        CVector( unsigned );
        virtual ~CVector();

         int& operator[] ( const int );
         const int& operator[] ( const int ) const;



};

And one 'CMatrix' derived from that:

(Toggle Plain Text)

class CMatrix : public CVector
{
        CVector *matrix;
        unsigned lin, col;
        string m_sNome;
public:
        CMatrix( const string&, const unsigned, const unsigned );
        ~CMatrix();

        CVector& operator[] ( const int );
        const CVector& operator[] ( const int ) const;
        friend CMatrix operator*( const CMatrix&, const CMatrix& );
};

Now in the constructor of CMatrix, i need to reserve dynamic memory for the array of CVector's, but I want each CVector inicialized with 'c' colums so I do this:

(Toggle Plain Text)

CMatrix( const string& str, const unsigned l, const unsigned c)
      lin( l ), col( c ), m_sNome( str )
{
        matrix = new CVector[ l ];
}

But if i do this, the each CVector object in the array is not incialized with c colums...

How can I do this???

Thanks in advance

robrosas · Nov 24th, 2005, 11:04 AM

I only made a fast overview of your code but I can see that you can solve your problem by initializing every CVector object in the matrix object with some loop. Like a for loop .

(Toggle Plain Text)

 for (int i =0;i< matrix array size ;i++) {
 matrix[i]= new CVector(c);
}

That should be in the constructor.

ivan · Nov 24th, 2005, 11:17 AM

nice first post..

-=PARADOX=- · Nov 24th, 2005, 3:16 PM

That makes sence :p

I'll try it

Thank you very nice

grumpy · Nov 25th, 2005, 3:48 AM

Unrelated to the problem, I know, but what is actually being achieved by deriving CMatrix from CVector?

-=PARADOX=- · Nov 25th, 2005, 4:53 AM

I guess nothing...

robrosas · Nov 25th, 2005, 8:42 AM

I saw that too grumpy, but he only asked for the constructor problem. Theres no sense why should CMatrix derives from Cvector. CMatrix can simply just "use" a Cvector and that's it.

-=PARADOX=- · Nov 25th, 2005, 8:46 AM

Ye you are right

Nov 24th, 2005, 9:59 AM	#1
-=PARADOX=- Programmer Join Date: Oct 2005 Location: Portugal Posts: 53 Rep Power: 3	Matrix Hi there again I have one annoying problem here :eek: I have one class 'CVector': (Toggle Plain Text) class CVector { int vector; unsigned n; // this is the number of elements public: CVector( ); CVector( unsigned ); virtual ~CVector(); int& operator[] ( const int ); const int& operator[] ( const int ) const; }; class CVector { int vector; unsigned n; // this is the number of elements public: CVector( ); CVector( unsigned ); virtual ~CVector(); int& operator[] ( const int ); const int& operator[] ( const int ) const; }; And one 'CMatrix' derived from that: (Toggle Plain Text) class CMatrix : public CVector { CVector matrix; unsigned lin, col; string m_sNome; public: CMatrix( const string&, const unsigned, const unsigned ); ~CMatrix(); CVector& operator[] ( const int ); const CVector& operator[] ( const int ) const; friend CMatrix operator( const CMatrix&, const CMatrix& ); }; class CMatrix : public CVector { CVector matrix; unsigned lin, col; string m_sNome; public: CMatrix( const string&, const unsigned, const unsigned ); ~CMatrix(); CVector& operator[] ( const int ); const CVector& operator[] ( const int ) const; friend CMatrix operator( const CMatrix&, const CMatrix& ); }; Now in the constructor of CMatrix, i need to reserve dynamic memory for the array of CVector's, but I want each CVector inicialized with 'c' colums so I do this: (Toggle Plain Text) CMatrix( const string& str, const unsigned l, const unsigned c) lin( l ), col( c ), m_sNome( str ) { matrix = new CVector[ l ]; } CMatrix( const string& str, const unsigned l, const unsigned c) lin( l ), col( c ), m_sNome( str ) { matrix = new CVector[ l ]; } But if i do this, the each CVector object in the array is not incialized with c colums... How can I do this??? Thanks in advance

Nov 24th, 2005, 11:04 AM	#2
robrosas Newbie Join Date: Nov 2005 Location: Puerto Rico Posts: 12 Rep Power: 0	Let me see.. I only made a fast overview of your code but I can see that you can solve your problem by initializing every CVector object in the matrix object with some loop. Like a for loop . (Toggle Plain Text) for (int i =0;i< matrix array size ;i++) { matrix[i]= new CVector(c); } for (int i =0;i< matrix array size ;i++) { matrix[i]= new CVector(c); } That should be in the constructor. __________________ From P.R. to the World!! RoBeRt Last edited by robrosas; Nov 24th, 2005 at 11:05 AM. Reason: forgot something

Nov 25th, 2005, 8:42 AM	#7
robrosas Newbie Join Date: Nov 2005 Location: Puerto Rico Posts: 12 Rep Power: 0	... I saw that too grumpy, but he only asked for the constructor problem. Theres no sense why should CMatrix derives from Cvector. CMatrix can simply just "use" a Cvector and that's it. __________________ From P.R. to the World!! RoBeRt

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Nov 24th, 2005, 11:17 AM	#3
ivan Professional Programmer Join Date: Sep 2005 Location: serbia & montenegro Posts: 482 Rep Power: 3	nice first post..

Nov 24th, 2005, 3:16 PM	#4
-=PARADOX=- Programmer Join Date: Oct 2005 Location: Portugal Posts: 53 Rep Power: 3	That makes sence :p I'll try it Thank you very nice

Nov 25th, 2005, 3:48 AM	#5
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,192 Rep Power: 5	Unrelated to the problem, I know, but what is actually being achieved by deriving CMatrix from CVector?

Nov 25th, 2005, 4:53 AM	#6
-=PARADOX=- Programmer Join Date: Oct 2005 Location: Portugal Posts: 53 Rep Power: 3	I guess nothing...

Nov 25th, 2005, 8:46 AM	#8
-=PARADOX=- Programmer Join Date: Oct 2005 Location: Portugal Posts: 53 Rep Power: 3	Ye you are right

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