Question

Say I have manually allocated a large portion of memory in C++, say 10 MB.

Say for the heck of it I want to store a few bits around the middle of this region.

How would I get at the memory at that location?

The only way I know of accessing raw memory is using array notation.

Answer 1

Array notation is just another way of writing pointers. You can use that, or use pointers directly like so:

char *the_memory_block = // your allocated block.
char b = *(the_memory_block + 10); // get the 11th byte, *-operator is a dereference.
*(the_memory_block + 20) = b; // set the 21st byte to b, same operator.

memcpy, memzero, memmove, memcmp and others may also be very useful, like this:

char *the_memory_block = // your allocated block.
memcpy(the_memory_block + 20, the_memory_block + 10, 1);

Of course this code is also the same:

char *the_memory_block = // your allocated block.
char b = the_memory_block[10];
the_memory_block[20] = b;

And so is this:

char *the_memory_block = // your allocated block.
memcpy(&the_memory_block[20], &the_memory_block[10], 1);

Also, one is not safer then the other, they are completely equivalent.