Problem with freeing 2D array

[dcdude]

Hello.

I am experiencing some problems when trying to free my 2D dynamic array.

The program appears to run perfectly fine if I do not try to free the array, but if I do, the program will freeze at some point with the cursor flashing as if it was waiting for me to input.

I know I should normally check for for return values, but I don't know how to do so. I have google'd but found many different versions of how to do so, so I don't know which one is the right way.

Here is a piece of my code. Please note that there are recursive functions. Could this interfere with freeing the array?

Would be grateful for advice of what's wrong, as well as any eventual code for the "if == NULL" check...

Thanks!

#include <stdio.h>
#include <stdlib.h>

openTile(int dimY, int dimX, int X, int Y)
{
	int i, j, count,k;
	char ch;
	char** minesArray;

	FILE *MinesFile;
	FILE *DisplayFile;

	// ALLOCATING A TWO-DIMENTIONAL DYNAMIC ARRAY FOR BOARD
	minesArray = (char**)malloc(dimY*sizeof(char*));
	for (i = 0; i < dimX; i++)
	{  
		minesArray[i] = (char*)malloc(dimX * sizeof(char));
	}

        // JUST A CHECK...
	if (check4Neighbours(dimY,dimX,X,Y) == 0)
	{
		if ((X > 0) && (Y > 0))
		{
                        // LOAD FILES FROM DISK TO RAM
			MinesFile = fopen("MinesFile.txt","r");
			for (i = 0; i < dimX; i++)
			{
				for (j = 0; j < dimY; j++)
				{
					minesArray[i][j] = fgetc(MinesFile);
				}
			}
			fclose(MinesFile);
			if (minesArray[X-1][Y-1] == '0')
			{
                                // EXECUTE CHANGES
				minesArray[X-1][Y-1] = '2';

				// SAVING DATA TO DISK
				MinesFile = fopen("MinesFile.txt","w+");
				for (i=0;i<dimX;i++)
				{
					for (j=0;j<dimY;j++)
					{
						fprintf(MinesFile,"%c",minesArray[i][j]);
					}
				}
				fclose(MinesFile);

				// RECURSING
				openTile(dimY, dimX, X-1, Y-1);
			}
		}


...



                if (Y > 0)
		{
                        // LOAD FILES FROM DISK TO RAM
			MinesFile = fopen("MinesFile.txt","r");
			for (i = 0; i < dimX; i++)
			{
				for (j = 0; j < dimY; j++)
				{
					minesArray[i][j] = fgetc(MinesFile);
				}
			}
			fclose(MinesFile);
			if (minesArray[X][Y-1] == '0')
			{
                                // EXECUTE CHANGES
				minesArray[X][Y-1] = '2';

				// SAVING DATA TO FILE
				MinesFile = fopen("MinesFile.txt","w+");
				for (i=0;i<dimX;i++)
				{
					for (j=0;j<dimY;j++)
					{
						fprintf(MinesFile,"%c",minesArray[i][j]);
					}
				}
				fclose(MinesFile);		

				// RECURSING
				openTile(dimY, dimX, X, Y-1);
			}
		}
	}
        // FREEING MEMORY
        for (i = 0; i < dimY; i++)
	{
		free(minesArray[i]);
	}
	free(minesArray);

[ShashiKantSuman]

minesArray = (char**)malloc(dimY*sizeof(char*));

look at the above section of code.
You are allocating memory dimy elements but you are only creating dimx string

for (i = 0; i < dimX; i++)
	{  
		minesArray[i] = (char*)malloc(dimX * sizeof(char));
	}

Now while freeing, you are try to free dimY string. if dimY > dimX then this program crash.

// FREEING MEMORY
        for (i = 0; i < dimY; i++)
	{
		free(minesArray[i]);
	}
	free(minesArray);

[dcdude]

Hi Shashi.

Thank you for your reply.

I changed dimY to dimX when freeing, using the same values as I used before (5 and 6), but the results were the same. The program froze.

What could be wrong?

[Bayint Naung]

Make sure you're not overflowing your heap.
And use a debugger!!

[Clairvoyant1332]

The dimY when freeing wasn't the problem. The dimX while mallocing is.

[Bayint Naung]

Did you read ShashiKantSuman post?
Read again carefully.

       minesArray = (char**)malloc(dimY*sizeof(char*));

       for (i = 0; i < dimX; i++)
	{  
		minesArray[i] = (char*)malloc(dimX * sizeof(char));
	}

What will happen if dimX > dimY ?

[dcdude]

Yeah, I just seen the problem... silly me. Thanks anyway for your replies all...