2010/4/27 spir ☣ <denis.s...@gmail.com>: > -1- untyped pointer allocation > In case of an untyped pointer, I read the compiler considers the target'size > is 1 byte. There certainly is an operation to allocate memory for the target > according to an existing piece of data. Something like > data := something > new(p,data); > // Either p points to data where it was > // or a new memory area is silently reserved, > // data copied there, and p holds its address.
New(p) doesn't work for untyped pointers, you have to use GetMem, FreeMem for example, where you give the amount of memory in bytes to allocate. After allocating memory you have to set/copy the data yourself. Target size of untyped pointer is 1 byte for pointer arithmetics. For example: var p: Pointer; pl: ^Node; begin p := someNode.next; pl := someNode.next; p := p + 1; // + 1 byte pl := pl + 1; // + SizeOf(Node) bytes end; > -2- reflexive pointing > The following works, but I do not understand how. ... > The issue is: ^endNode holding a pointer to endNode, how is this kind of > infinite self-referencing loop resolved by the compiler, at definition time? The compiler doesn't care what value is written there, as long as type is compatible. > PS: How else terminate a linked list in Pascal? (I must put something in the > .next field of the last actual node, and this thing must be a List, ie a node > pointer.) Put 'nil', and then while traversing the list when you encounter that pointer to next node is nil then you are at the end of the list. -- cobines _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
