How to get the size of dynamically allocated 2d array

Question

I have dynamically allocated 2D array. Here is the code

int **arrofptr ;
arrofptr = (int **)malloc(sizeof(int *) * 2);
arrofptr[0] = (int *)malloc(sizeof(int         


        

Answer 1

You can't get the length of dynamically allocated arrays in C (2D or otherwise). If you need that information save it to a variable (or at least a way to calculate it) when the memory is initially allocated and pass the pointer to the memory and the size of the memory around together.

In your test case above sizeof is returning the size of the pointer, and thus your calculation the size of the pointers is usually 4, this is why you got 4 and is likely to have the trivial result of 4, always.