Question

Can you please explain to me what is happening here?

char data[128]; // Create char array of size 128.
long * ptr;     // Create a pointer.
ptr = (long *) data;   // ??

Mainly, what does the (long *) mean?

Does it mean that the data is of type char, and I am casting the reference to data as a reference to a long?

Thank you.

Answer 1

It is casting the data pointer as a pointer to a long.

The line:

 char data[128];

will allocate 128 bytes of memory and treat that data as characters. The code:

 long * ptr;
 ptr = (long *) data;

allocates a pointer to a long, and sets that pointer to point at the memory allocated by char data[128];.

You can reference this memory by data[x] to get the xth character starting at the beginning of this memory block. Or you can reference this memory by ptr[x] to get the xth long starting at the beginning of this memory block. Just note that each long takes up more storage than each character. It is probably 8 bytes – so you can go up to data[127] or ptr[15].