_ASSERTE(_BLOCK_TYPE_IS_VALID(pHead->nBlockUse)) error

Question

I'm trying to figure out why my program fails when I run. So far when I run my program it fails on me. I debugged the error and it brings me to dbgdel.cpp. Line 32 " _ASSERTE(_BLOCK_TYPE_IS_VALID(pHead->nBlockUse));". I've searched for the answer to no avail, but it has something to do with my memory leak?

Here is my header:

#include <iostream>
using namespace std;
namespace project
{
#ifndef MATRIX_H
#define MATRIX_H

typedef int* IntArrayPtr;
class Matrix
{
public:
    friend ostream& operator<<(ostream& out, Matrix& object);
    //friend istream& operator>>(istream& in, Matrix& theArray);
    //Default Constructor
    Matrix();
    Matrix(int max_number_rows, int max_number_cols, int intial_value);
    //Destructor
    ~Matrix();
    //Copy Constructor
    Matrix(const Matrix& right_side);
    //Assignment Operator
    Matrix& operator=(const Matrix& right_side);

    void Clear();
    int Rows();
    int Columns();
    bool GetCell(int x,int y, int& val);
    bool SetCell(int x,int y, int val);
    int getNumber(int r, int c);
    //void Debug(ostream& out);
private:
    int initialVal;
    int rows;
    int cols;
    IntArrayPtr *m;
};
#endif
}

My implementation file:

#include <iostream>
#include "Matrix.h"
 using namespace project;
using namespace std;

namespace project
{
Matrix::Matrix()
{
typedef int* IntArrayPtr;
IntArrayPtr *m = new IntArrayPtr[1];
for(int i = 0; i < 1; i++)
    m[i] = new int[1];

for(int r = 0; r < 1; r++)
    for(int c = 0; c < 1;c++)
        m[r][c] = 0;
}
Matrix::Matrix(int max_number_rows, int max_number_cols, int initial_value)
{
initialVal = initial_value;
rows = max_number_rows;
cols = max_number_cols;
IntArrayPtr *m = new IntArrayPtr[rows];
for(int i = 0; i < rows; i++)
    m[i] = new int[cols];

for(int r = 0; r < max_number_rows; r++)
    for(int c = 0; c < max_number_cols;c++)
        m[r][c] = initial_value;

}
Matrix::~Matrix()
{
for(int i = 0; i <= rows; i++)
    delete [] m[i];
delete [] m;
}
void Matrix::Clear()
{
for(int r = 0; r < rows; r++)
    for(int c = 0; c < cols;c++)
        m[r][c] = initialVal;
}

int Matrix::Rows()
{
return rows;
}

int Matrix::Columns()
{
return cols;
}

bool Matrix::GetCell(int x,int y, int& val)
{
if(x < rows || y < cols)
    return false;
else
{
    val =   m[x - 1][y - 1];
    return true;
}
}

bool Matrix::SetCell(int x, int y, int val)
 {
if(x < rows || y < cols)
    return false;
else
{
    m[x - 1][y - 1] = val;
    return true;
}
}
int Matrix::getNumber(int r, int c)
{
return m[r][c];
}

ostream& operator<<(ostream& out, Matrix& object)
{

for(int r = 0; r < object.rows; r++)
{
    for(int c = 0; c < object.cols; c++)
    {
        out << " " << object.m[r][c];
    }
out << endl;
}
return out;
}

Matrix& Matrix::operator=(const Matrix& right_side)
{
if (this != &right_side)
{
    rows = right_side.rows;
    cols = right_side.cols;
    delete[] m;
    IntArrayPtr *m = new IntArrayPtr[rows];
    for(int i = 0; i < rows; i++)
        m[i] = new int[cols];

    for(int r = 0; r < rows; r++)
        for(int c = 0; c < cols;c++)
            m[r][c] = right_side.initialVal;
}
return *this;
}

/*
void Matrix::Debug(ostream& out)
{
out << "Number of rows = " << rows << endl;
out << "Number of columns = " << cols << endl;
out << "Initializer = " << initialVal << endl;
out << "Current contents of the matrix: " << endl;
out << m << endl;
}
*/
/*
istream& operator >>(istream& in, Matrix& theArray)
{
in >> 


}

void interfaceMatrix()
{
int userChoice, rows, columns, value;

cout << "Default matrix or custom(1 for default, 0 for custom): ";
cin >> userChoice;
    if (userChoice == 1)
    {
        Matrix object;
        return object;
    }
    else if(userChoice == 0)
    {
        cout << "Enter number of rows: ";
        cin >> rows;
        cout << "Enter number of columns: ";
        cin >> columns;
        cout << "Enter initial value of each element: ";
        cin >> value;
        if(rows <= 0 || columns <= 0)
        {
            cout << "Invalid input." << endl;
            exit(1);
        }
        else
        {
            Matrix object(rows, columns, value);
            return object;
        }
    }
    else
    {
        cout << "Invalid choice." << endl;
        exit(1);
    }

}
*/
}

In my driver I just put Matrix test(2,2,2), so I can create a 2 x 2 array with initial value of 2 for each element. I get the above error.

Answer 1

You are allocating rows number of rows, but deallocating rows+1 number of rows. Check the destructor. <= must be <.

Besides this there are a lot of other [potential] errors in your code:

• you are setting the local m variable instead of setting the m data member of your class (that's why I have the convention to always precede data members by m_ to prevent this kind of confusion). This error appears both in the constructor and the assignment operator.
• you use rows to allocate the matrix, but max_number_rows to initialize the matrix. Although it works correctly now, it may lead to errors if row is initialized differently later (eg if row is initialized with std::max(max_number_rows,1000) . Your code in the assignment operator is better.
• your if-test in GetCell and SetCell is incorrect. It should probably be >= instead of <
• the assignment operator copies the size of the matrix, but assigns all cells an initialValue. This is not an assignment. This implementation might/will confuse the rest of the code.
• the typedef of IntArrayPtr is unnecessary

Answer 2

two issues:

1. You are not allocating any value into the "m" member of your object, you are allocating into local variables named "m"
2. you are over deallocating by looping from i=0 to i <= rows, you want i=0 to i < rows