2010/9/22 Graeme Geldenhuys <graemeg.li...@gmail.com>: > type > TAtomArray = array[0..0] of TAtom; > PAtomArray = ^TAtomArray; > > Now if I change TAtomArray to the follow, then my code doesn't work. :-) > > TAtomArray = array of TAtom; // a dynamic array > > So what exactly is the difference between these two? > > TAtomArray = array[0..0] of TAtom; > vs > TAtomArray = array of TAtom; > > > Is array[0..0] not actually a dynamic array, but just a static array > with a single item? If so, then why does the returned value from the C > API call, which returns a pointer to an array of culong's (normally > more that one item) work? Somewhere I'm getting confused with all > this, but would love to understand it correctly, and why it works. :) >
In brief AFAIK: type T1 = array[l..h] of T3; T2 = array of T3; says that T1 is a value type and T2 is a pointer type (ptr casted deref of a T2 typed variable may(? depends on implementation) safely alias a T1 typed entity, but a pointer to a first element of a T1 value can't be safely aliased to a T2 typed entity). Additionally dynamic arrays are a compiler handled structures, the differences are similar to those between shortstrings and AnsiStrings types. -- bflm freepascal-bits.blogspot.com _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
