2D Arrays in C Using malloc

Pointers can be easily used to create a 2D array in C using malloc. The idea is to first create a one dimensional array of pointers, and then, for each array entry, create another one dimensional array. Here's a sample code:

double** theArray;
theArray = (double**) malloc(arraySizeX*sizeof(double*));
for (int i = 0; i < arraySizeX; i++)
   theArray[i] = (double*) malloc(arraySizeY*sizeof(double));

Voila!

What I usually do is create a function called Make2DDoubleArray that returns a (double**) and then use it in my code to declare 2D arrays here and there

double** Make2DDoubleArray(int arraySizeX, int arraySizeY) {
double** theArray;
theArray = (double**) malloc(arraySizeX*sizeof(double*));
for (int i = 0; i < arraySizeX; i++)
   theArray[i] = (double*) malloc(arraySizeY*sizeof(double));
   return theArray;
} 

Then, inside the code, i would use something like

double** myArray = Make2DDoubleArray(nx, ny);

Voila!

Of course, do not forget to remove your arrays from memory once you're done using them. To do this

for (i = 0; i < nx; i++){
   free(myArray[i]);
}
free(myArray);

UPDATE: JULY 10, 2008
As was noted by an anonymous comment, a great advantage of declaring a 2D array in this manner is the ability to use it as myArray[i][j], a very intuitive form.

Cite as:
Saad, T. "2D Arrays in C Using malloc". Weblog entry from Please Make A Note. http://pleasemakeanote.blogspot.com/2008/06/2d-arrays-in-c-using-malloc.html