What is the maximum size of buffers memcpy/memset etc. can handle?

Question

What is the maximum size of buffers memcpy and other functions can handle? Is this implementation dependent? Is this restricted by the size(size_t) passed in as an argument?

Answer 1

Functions normally use a size_t to pass a size as parameter. I say normally because fgets() uses an int parameter, which in my opinion is a flaw in the C standard.

size_t is defined as a type which can contain the size (in bytes) of any object you could access. Generally it's a typedef of unsigned int or unsigned long.
That's why the values returnes by the sizeof operator are of size_t type.

So 2 ** (sizeof(size_t) * CHAR_BIT) gives you a maximum amount of memory that your program could handle, but it's certainly not the most precise one.
(CHAR_BIT is defined in limits.h and yields the number of bits contained in a char).