How do I correctly set up, access, and free a multidimensional array in C?

Question

I have seen dozens of questions about “what’s wrong with my code” regarding multidimensional arrays in C. For some reason people can’t seem to wrap their head around what is

Answer 1

If you want to use a typedef'd array, it is even simpler.

Say you have in your code typedef int LabeledAdjMatrix[SIZE][SIZE];

You can then use:

LabeledAdjMatrix *pMatrix = malloc(sizeof(LabeledAdjMatrix));

Then you can write:

for (i=0; i

Because pArr is a pointer to you matrix and * has lower priority than [];

That is why a mode common idiom is to typedef the row:

typedef int LabeledAdjRow[SIZE];

Then you can write:

LabeledAdjRow *pMatrix = malloc(sizeof(LabeledAdjRow) * SIZE);
for (i=0; i

And you can memcpy all that directly:

LabeledAdjRow *pOther = malloc(sizeof(LabeledAdjRow) * SIZE);
memcpy(pOther, pMatrix, sizeof(LabeledAdjRow) * SIZE);