Question

So I have a class called MatrixMxN, in the constructor it has parameters row, column. I am attempting to allocate memory for a 2D array with dimensions row, column, although I am getting a problem with doing this..
(I am overriding the parenthesis operator to assign values to each entry)

{
    MatrixMxN coord(4, 1);
    coord(0, 0) = 1.0;
    coord(0, 1) = 1.0;
    coord(0, 2) = 1.0;
    coord(0, 3) = 1.0;
}

The problem I am facing seems to be when the deconstructor is called and I receive the error:-

Windows has triggered a breakpoint in MatrixTest.exe.
This may be due to a corruption of the heap, which indicates a bug in MatrixTest.exe or any of the DLLs it has loaded.

The snippet from my matrix class is as follows;

typedef float* floatPtr;
class MatrixMxN {
private:
    float** entry;
    int rows;
    int cols;

public:
    MatrixMxN(int r, int c) {
        rows = r;
        cols = c;

        //Create a matrix
        if(rows > 0 && cols > 0) {
            //Declare an array of pointers
            entry = new floatPtr[rows];

            //Declare each array
            for(int i=0; i<rows; i++) {
                entry[i] = new float[cols];
            }

            this->empty();
        }
    }
    ~MatrixMxN() {
        //Free memory
        for(int i=0; i<rows; i++) {
            delete[] entry[i];
        }

        //Free pointers array
        delete[] entry;
    }

    void empty() {
        for(int i=0; i<rows; i++) {
            for(int j=0; j<cols; j++) {
                entry[i][j] = 0;
            }
        }
    }

    // Assignment operator
    void operator=(MatrixMxN& other) {
        //Check they are the same size
        assert(rows == other.rows && cols == other.cols);

        //Copy
        for(int i=0; i<rows; i++) {
            for(int j=0; j<cols; j++) {
                entry[i][j] = other(i, j);
            }
        }
    }
    float& operator()(const int irow, const int icol) {
        //Check they are not out of bounds
        assert ( (irow >= 0 && irow < rows) ||  (icol >= 0 && icol < cols) );

        return entry[irow][icol];
    }
...

The part which is tripping up an error is in the deconstructor inside the loop;

    //Free memory
    for(int i=0; i<rows; i++) {
        delete[] entry[i];
    }

The dbgheap.c file throws the error on the first attempt to delete[] entry[i] where i =0. Although when printing the matrix it works fine as intended but there appears to be an error here. Hopefully I have provided enough information here, thanks.

Edit1: Included assignment operator overload
Edit2: Included () overload

Answer:
The problem was I was entering the values in a transpose manner rather than how I had it. The memory was being corrupted here, thanks for all the help.

Answer 1

This may not be the cause but there is no copy constructor or assignment operator defined for the class MatrixMxN: either define them or make the object non-copyable by declaring them private.

While not the problem in this example, delete[] will be invoked on an uninitialized pointers in the destructor if rows > 0 but cols <= 0. In the constructor, entry is only initalized if rows > 0 && cols > 0. If rows > 0 but cols <= 0 the following for loop in the destructor still invokes delete[] entry[i];:

for(int i=0; i<rows; i++) {
    delete[] entry[i]; // entry unitialized
}

followed by:

delete[] entry; // entry unitialized

EDIT:

This assert in operator() is incorrect:

assert ( (irow >= 0 && irow < rows) ||  (icol >= 0 && icol < cols) );

it should be using &&:

assert ( (irow >= 0 && irow < rows) &&  (icol >= 0 && icol < cols) );