...
The following standard library functions take a pointer argument and a size argumentsize argument, with the constraint that the pointer must point to a valid memory object of at least the number of bytes or wide characters (as appropriate) of elements indicated by the size argument.
...
1 Takes two pointers and an integer, but the integer only specifies the length of the element count of the output buffer. not the input buffer.
2 Takes two pointers and an integer, but the integer only specifies the length of the element count of the input buffer, not the output buffer.
3 Takes two pointers and two integers; each integer corresponds to the length of the element count of one of the pointers.
4 Takes a pointer and two size-related integers; the first size-related integer parameter specifies the size the number of bytes available in the buffer, the second size-related integer parameter specifies the number of bytes to write within the buffer.
...
The following standard library functions take two pointer arguments and a size argument, with the constraint that both pointers must point to valid memory objects of at least the number of bytes or wide characters as appropriate, of elements indicated by the size argument.
...