Pointers and references: Difference between revisions

==[[Pop11]]==

[[Category:Pop11]]

Pop11 uses reference model, conceptually all Pop11 data consists

of references. Therefore, normally there is no need for explicit

references:

vars vec1, vec2;

;;; Create a vector and assign (reference to) it to vec1

consvector("a", "b", "c", 3) -> vec1;

;;; Copy (reference to) vector

vec1 -> vec2;

;;; Print value of vec1

vec1 =>

;;; Change first element of vec2

"d" -> vec2(1);

;;; Print value of vec1 -- the value changes because vec1 and

;;; vec2 reference the same vector

vec1 =>

However, if one needs extra indirection one can get it:

vars ref1, ref2;

;;; Allocate a reference to number 42

consref(42) -> ref1;

;;; Copy reference

ref1 -> ref2;

;;; print value

cont(ref2) =>

;;; Change referenced value

17 -> cont(ref2);

;;; print value of first reference

cont(ref1) =>

Standard Pop11 does not allow pointer arithmetics or address operator.

There is a low-level extension (Syspop11) which has C-like pointers

(with pointer arithmetics), but those does not count as "basic data

operation".