Problem with accessing private members of inherited template class

[arthurav]

I have the following program :

#include<iostream>
#include<string>
#include<conio.h>
using namespace std;

template <class T>
class matrice
{
    T **a;
    int m,n;
public: 
	matrice();
    matrice(int,int,int);
    matrice(char *);
    matrice(int,int,T **);
    matrice(matrice &x);
    ~matrice(){};

	template <class U>
    friend ostream &operator <<(ostream &,matrice<U> &);

    int getNrLinii(){
        return m;
    }
    int getNrColoane(){
        return n;
    }
    void setElement(int,int,T);

};

template <class T>
ostream &operator<<(ostream &os, matrice<T> &b){
    int i,j;
    for(i=0;i<b.m;i++){
        for(j=0;j<b.n;j++){
            os<<b.a[i][j]<<" ";
        }
        os<<endl;
    }
    return os;
}

matrice<char *>::matrice(int linii,int col,int ini=1):m(linii),n(col){
    int i,j;
    a=new char**[m];
    for(i=0;i<m;i++){a[i]=new char*[n];}
	if(ini){
    for(i=0;i<m;i++)
        for(j=0;j<n;j++){
            cout<<"a["<<i<<"]["<<j<<"]= ";
            char *tmp;
            tmp=new char[100];
            cin>>tmp;
            a[i][j]=new char[strlen(tmp)+1];
            strcpy(a[i][j],tmp);
            delete tmp;
        }
	}
}

matrice<double >::matrice(int linii,int col,int ini=1):m(linii),n(col){
    int i,j;
    a=new double*[m];
    for(i=0;i<m;i++){a[i]=new double[n];}
    if(ini){
	for(i=0;i<m;i++)
        for(j=0;j<n;j++){
            cout<<"a["<<i<<"]["<<j<<"]= ";
            cin>>a[i][j];
        }
	}
}

matrice<char *>::matrice():m(1),n(1){
    
    a=new char**[];
	a[0]=new char*[1];
	a[0][0]=new char[1];
	strcpy(a[0][0],"");
}

matrice<double >::matrice():m(1),n(1){
    int i,j;
    a=new double*[1];
    a[0]=new double[1];
	a[0][0]=0;
}

matrice<double>::matrice(char *filename){
	FILE *f;
	f=fopen(filename,"r");
	fscanf(f,"%i %i\n",&m,&n);
	a=new double*[m];
	for(int i=0;i<m;i++)a[i]=new double[m];
	for(int i=0;i<m;i++){
		for(int j=0;j<n;j++)
			fscanf(f,"%lf ",&(a[i][j]));
		fscanf(f,"\n");
	}
}

matrice<char*>::matrice(char *filename){
	FILE *f;
	f=fopen(filename,"r");
	fscanf(f,"%i %i\n",&m,&n);
	a=new char**[m];
	for(int i=0;i<m;i++)a[i]=new char*[m];
	for(int i=0;i<m;i++){
		for(int j=0;j<n;j++){
			char *tmp;
            tmp=new char[100];
			fscanf(f,"%s ",&tmp);
            a[i][j]=new char[strlen(tmp)+1];
            strcpy(a[i][j],tmp);
            delete tmp;
		}
		fscanf(f,"\n");
	}
}

matrice<char *>::matrice(int linii,int col, char*** b):m(linii),n(col){
    int i,j;
    a=new char**[m];
    for(i=0;i<m;i++){a[i]=new char*[n];}
    for(i=0;i<m;i++)
        for(j=0;j<n;j++){
            cout<<"a["<<i<<"]["<<j<<"]= ";
            a[i][j]=new char[strlen(b[i][j])+1];
            strcpy(a[i][j],b[i][j]);
        }
}

matrice<double >::matrice(int linii,int col,double **b):m(linii),n(col){
    int i,j;
    a=new double*[m];
    for(i=0;i<m;i++){a[i]=new double[n];}
    for(i=0;i<m;i++)
        for(j=0;j<n;j++){
            a[i][j]=b[i][j];
        }
}

matrice<double>::matrice(matrice<double> &b):m(b.m),n(b.n){
    a=new double*[m];
    for(int i=0;i<m;i++){a[i]=new double[n];}
    for(int i=0;i<m;i++)
        for(int j=0;j<n;j++){
            a[i][j]=b.a[i][j];
        }
}

matrice<char *>::matrice(matrice<char*> &b):m(b.m),n(b.n){
    int i,j;
    a=new char**[m];
    for(i=0;i<m;i++){a[i]=new char*[n];}
    for(i=0;i<m;i++)
        for(j=0;j<n;j++){
            cout<<"a["<<i<<"]["<<j<<"]= ";
            a[i][j]=new char[strlen(b.a[i][j])+1];
            strcpy(a[i][j],b.a[i][j]);
        }
}

class matriceDouble:public matrice<double>{
public:
	friend matriceDouble operator+(matriceDouble &a,matriceDouble &b){
		if((a.m==b.m)&&(a.n==b.n)){
			matriceDouble c=a;
			for(int i=0;i<a.m;i++)
				for(int j=0;j<a.n;j++)
					c.a[i][j]=c.a[i][j]+b.a[i][j];
		}
		else{matriceDouble c;}
		return c;
	}
};

void main (int argc, char * const argv[]) {
    //matrice<char *> m1(2,2);
	matrice<double> m1("matrice1.txt");
	matrice<double> m2("matrice2.txt");
    cout<<m1;
	cout<<endl;
	cout<<m2<<endl;

	matrice<double> m3=m2;
	cout<<m3;
	matriceDouble x;
    getch();
}

For the matriceDouble I get this error in the friend operator+ procedure:

1>c:\documents and settings\administrator\desktop\proiect\proiect\proiect.cpp(232): error C2248: 'matrice<T>::m' : cannot access private member declared in class 'matrice<T>'

Why is this?
Thank you.

[Fbody]

classes have 3 access levels private, protected, and public.

The private level prevents access to members by any code outside the containing class, including derived classes.

The protected access level is approximately the same as the private level, but it allows derived classes access to members of that access level.

You need to declare 'a'. 'm', and 'n' as protected if you want your derived class "matriceDouble" to be able to access them.