On 3/17/07, Jm lists <[EMAIL PROTECTED]> wrote: snip
What's the difference between Perl's reference and C's pointer? I'm always confused about them.Thanks for any direction.
snip
In ANSI C a pointer is an address into raw memory. How much memory it returns is based on its type which is determined either by declaration or casting. Static arrays are implemented as pointers that cannot be changed and dynamic arrays are created using pointers. There is no difference between saying *p and p[0]. Pointers can address any memory, although accessing protected memory can cause a segfault. In Perl the reference is a address of an entry in the symbol table. That entry has a type which can be determined by calling the ref function. References have nothing to do with how arrays are implemented except that arrays have an entry in the symbol table like everything else. Inside of Perl it is impossible to have a reference to something that does not exist* since things only get garbage collected when their reference count drops to zero. So, it all comes down to this, a pointer is an unconstrained address into memory and a reference is the result of the symbol table look up. Hope this helps. * If you are using XS, or an XS based module, then it is possible for the C code to decrement the reference count manually. -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/
