4. Pointer Fehler?

Pointer Fehler?

  • ?

    Ich bin dran ne matrixklasse zu schrieben in MSVC 08. Die Klasse kompiliert fehlerfrei. Wenn ich die konsole jedoch starte um das ganze zu testen erhalte ich folgende fehlermeldung:

    'matrix.exe': Loaded 'C:\Documents and Settings\clypto89\My Documents\Visual Studio 2008\Projects\matrix\Debug\matrix.exe', Symbols loaded.
    'matrix.exe': Loaded 'C:\WINDOWS\system32\ntdll.dll'
    'matrix.exe': Loaded 'C:\WINDOWS\system32\kernel32.dll'
    'matrix.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.21022.8_x-ww_597c3456\msvcp90d.dll', Symbols loaded.
    'matrix.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.21022.8_x-ww_597c3456\msvcr90d.dll', Symbols loaded.
    First-chance exception at 0x102d31ea (msvcr90d.dll) in matrix.exe: 0xC0000005: Access violation reading location 0xfeeefee2.
    Unhandled exception at 0x102d31ea (msvcr90d.dll) in matrix.exe: 0xC0000005: Access violation reading location 0xfeeefee2.

    #include <iostream>
#include <math.h>
using namespace std;
class matrix
{
public:
	matrix(int n);
	matrix(int rows=0, int cols=0);
	~matrix();
	int matrix::getR();
	int matrix::getC();
	double** matrix::getE();
	double* matrix::getR(int);
	double* matrix::getC(int);
	double& matrix::operator()(int, int);
	double matrix::operator() (int, int) const;
	friend ostream& operator<<(ostream&, const matrix&);
	friend istream& operator>>(istream& , matrix&);
	matrix matrix::zeros(int,int);
	matrix matrix::identity(int,int);
	friend bool operator==(double&,const matrix&,const matix&);
	friend matrix operator+(const matrix&,const matrix&);
	friend matrix operator-(const matrix&,const matrix&);
	friend matrix operator*(const matrix&,const matrix&);
	friend matrix operator-(matrix&);
	friend matrix& operator+=(matrix&,const matrix&);
	friend matrix& operator-=(matrix&,const matrix&);
	friend matrix& operator*=(matrix&,const matrix&);
	matrix& matrix::permutation(int,int,matrix&);
	matrix& matrix::transposition(int,double,matrix&);
	matrix& matrix::rowaddition(int,int,double,matrix&);
private:
	int rows;
	int cols;
	double** element;
};
matrix::matrix(int n)
{
	rows=n;
	cols=n;
	element=NULL;
	element = new double *[rows];
	for(int i =0; i < rows; ++i)
	{
		element[i]=new double[cols];
	}
}

matrix::matrix(int m, int n)
{
	rows=m;
	cols=n;
	element=NULL;
	element = new double *[rows];
	for(int i =0; i < rows; ++i)
		element[i]=new double[cols];

}

matrix::~matrix()
{
    for (int i = 0; i < rows ; ++i)
	{
        delete [] elements[i];
    }
	delete [] elements; 
} 

int matrix::getR()
{
	return rows;
}

int matrix::getC()
{
	return cols;
}

double** matrix::getE()
{
	return element;
}

double& matrix::operator() (int m, int n)
{
	return element[m-1][n-1];
}

double matrix::operator() (int m, int n) const
{
	return element[m-1][n-1];
}

ostream& operator<<(ostream & result, const matrix& A)
{
	for(int i = 0; i < A.rows; ++i)
	{
		cout<<endl;
		for(int j=0; j < A.cols; j++)
			result << A.element[i][j]<<"\t";
	}
	cout<<endl;
	return result;
}

istream& operator>> (std::istream& in, matrix& A)
{
	for(int i = 0; i < A.rows; ++i)
	{
	    for(int j = 0; j < A.cols; ++j)
		{
			std::cout << "a[" << i+1 << "][" << j+1 << "]=";
			in >> A.element[i][j];
	    }
    }
	return in;
}

matrix matrix::zeros(int m, int n)
{
	matrix A(m,n);
	for(int i = 0; i < m; ++i)
	{
	    for(int j = 0; j < n; ++j)
		{
			A.element[i][j]=0;
	    }
    }
	return A;
}

matrix matrix::identity(int m, int n)
{
	matrix A(m,n);
	for(int i = 0; i < m; ++i)
	{
	    for(int j = 0; j < n; ++j)
		{
			if(i != j) 
			{
				A.element[i][j] = 0;
			} else {
				A.element[i][j] = 1;
			}
	    }
    }
	return A;
}

bool operator==(double& precision, const matrix& A, const matix& B)
{
	precision = fabs(precision);
	for(int i = 0; i < A.rows; ++i)
	{
		for(int j = 0; j < A.cols; ++j)
		{
			if(fabs( A.element[i][j]-B.element[i][j] )>precision) 
			{
				return false;
			} 
	    }
    }
	return true;
}

matrix operator+(const matrix& A, const matrix& B)
{
	matrix C(A.rows,A.cols);
	for(int i = 0; i < A.rows; ++i)
		for(int j = 0; j < A.cols; ++j)
			C.element[i][j]=A.element[i][j]+B.element[i][j];
	return C;
}

matrix operator-(const matrix& A, const matrix& B)
{
	matrix C(A.rows,A.cols);
	for(int i = 0; i < A.rows; ++i)
		for(int j = 0; j < A.cols; ++j)
			C.element[i][j]=A.element[i][j]-B.element[i][j];
	return C;
}

matrix operator*(const matrix& A, const matrix& B)
{
	double sum = 0;
	matrix C(A.rows,B.cols);
	for(int i = 0; i < A.rows; ++i)
		{
		for(int j = 0; j < B.cols; ++j)
			{
			for(int k = 0; k < A.cols; ++k)
				{
				sum +=A.element[i][k]*B.element[k][j];
				}
			C.element[i][j] = sum;
			sum = 0;
			}
		}
	return C;
}

matrix operator-(matrix& A)
{
	for(int i = 0; i < A.rows; ++i)
		for(int j = 0; j < A.cols; ++j)
			A.element[i][j]=-A.element[i][j];
	return A;
}

matrix& operator+=(matrix& A,const matrix& B)
{
	for(int i = 0; i < A.rows; ++i)
		for(int j = 0; j < A.cols; ++j)
			A.element[i][j]+=B.element[i][j];
	return A;
}

matrix& operator-=(matrix& A,const matrix& B)
{
	for(int i = 0; i < A.rows; ++i)
		for(int j = 0; j < A.cols; ++j)
			A.element[i][j]-=B.element[i][j];
	return A;
}

matrix& operator*=(matrix& A,const matrix& B)
{
	double sum = 0;
	matrix C(A.rows,B.cols);
	for(int i = 0; i < A.rows; ++i)
		{
		for(int j = 0; j < B.cols; ++j)
			{
			for(int k = 0; k < A.cols; ++k)
				{
				sum +=A.element[i][k]*B.element[k][j];
				}
			A.element[i][j] = sum;
			sum = 0;
			}
		}
	return A;
}

matrix& matrix::permutation(int i,int j,matrix& A)
{
	double store;
	int k = 0;
	for(; k < A.cols; ++k)
		store = A.element[j][k];
		A.element[j][k]=A.element[i][k];
		A.element[i][k]=store;
	return A;
}

matrix& matrix::transposition(int m, double y, matrix& A)
{
	for(int k = 0; k < A.cols; ++k)
		A.element[m][k]+=y*A.element[m][k];
	return A;
}

matrix& matrix::rowaddition(int from,int to,double y,matrix& A)
{
	for(int k = 0; k < A.cols; ++k)
		A.element[to][k]+=y*A.element[from][k];
	return A;
}

int main()
{
int n;
cout<<"enter the size of the matrix:";
cin>>n;
matrix A(n,n);
matrix B(n,n);
matrix C(n,n);
cin>>A;
cin>>B;
C=A+B;
cout<<A;
cout<<B;
cout<<C;
C=A-B;
cout<<C;
C=A*B;
cout<<C;
cin>>n;
return 0;
};

    mein gefühl sagt mir das irgendwas mit nem pointer nicht in ordnung ist aber ich finde den fehler nicht. Ich wäre sehr dankbar um hilfe.

    mit freundlichen grüssen.

    hans

    0
  • Z

    First-chance exception at 0x102d31ea (msvcr90d.dll) in matrix.exe: 0xC0000005:
    Access violation reading location 0xfeeefee2

    Da wird der debugger bestimmt auch n break vorgeschlagen habe,...

    a) zeige mal die stelle wo
    b) meine vermutung: uninitialisierter ptr

    grüüüße

    0
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