Friday, March 4, 2011

Harbour/xharbour Diff (4/57) - HASH ARRAYS by Przemyslaw Czerpak

Both compilers have support for hash arrays. They are similar to normal arrays but also allow to use non integer values as indexes like string, date, non integer number or pointer (in Harbour) items.

They can be created using => for list of keys and values enclosed
inside {}, f.e.:
hVal := { "ABC" => 123.45, ;
100.1 => date(), ;
100.2 => 10, ;
100 => 5, ;
date()-1 => .t. }
and then items can be accessed using [] operator, f.e.:
? hVal[ "ABC" ] // 123.45
? hVal[ 100 ] // 5
? hVal[ date()-1 ] // .t.
? hVal[ 100.2 ] // 10
? hVal[ 100.1 ] // date()

By default hash items in both compiler support automatic adding new elements
on assign operation. It can be disabled using one of hash item functions.
Harbour has additional extension which allows to enable autoadd with default
values also for access operation and reference operator. It also supports
well passing hash array items by reference and has some other minor

xHarbour does not support autoadd on access or reference operations and
passing hash array items by reference does not work (see passing array and
hash item by reference).

Both compilers have set of functions to make different operations on hash
arrays which give similar functionality. In Harbour they use HB_H prefix
(f.e. HB_HSCAN()) in xHarbour H prefix (f.e. HSCAN())

xHarbour has additional functionality which can be enabled for each hash
array using HSetAACompatibility() function. It's an index where is stored
information about the order in which items were added to hash array and
set of functions with HAA prefix to operate on hash array items using this
index instead of real position in hash array, i.e. HAAGETVALUEAT() which
works like HGETVALUEAT().

In Harbour such functionality also exists and it's enabled by HB_HKEEPORDER() function but the internal implementation is completely different. Harbour does not emulate associative arrays by special index which keeps assign order but it uses real natural order in hash array. It means that associative array indexes are equal to regular hash indexes so it does not need any translation between them and Harbour users can use regular hash array functions for associative array indexes. So separated functions for accessing by other index are not necessary. The Harbour implementation is also more efficient because it does not introduce linear index updated each time new key is added to hash array.

Harbour emulates HAA*() xHarbour functions in XHB library but only for
compatibility with existing xHarbour code.

No comments:

Post a Comment

Welcome to Clipper... Clipper... Clipper

In 1997, then using Delphi 3, I had already created 32-bits Windows applications for HRIS, ERP and CRM. In 2007, using Ruby on Rails, an AJAX powered CRM site running on Apache & MySQL was created and I am now using Visual Studio .Net 2008 to create web-based projects and Delphi 7 for Win32 applications using SQL2005 & DBFCDX.

So, why then am I reviving the Original Clipper... Clipper... Clipper via a Blog as CA-Clipper is a programming language for the DOS world ? Believe it or not, there are still some clients using my mission-critical CA-Clipper applications for DOS installed in the late 80's and up to the mid 90's. This is testimony to CA-Clipper's robustness as a language :-)

With the widespread introduction of Windows 7 64-bits as the standard O/S for new Windows based PCs & Notebooks, CA-Clipper EXE simply will not work and it has become imperative for Clipper programmers to migrate immediately to Harbour to build 32/64 bits EXEs

Since 28th January 2009, this blog has been read by 134,389 (10/3/11 - 39,277) unique visitors (of which 45,151 (10/3/11 - 13,929) are returning visitors) from 103 countries and 1,574 cities & towns in Europe (37; 764 cities), North America (3; 373 cities) , Central America & Caribeans (6; 13 cities), South America(10; 226 cities), Africa & Middle-East (12; 44 cities) , Asia-Pacific (21; 175 cities). So, obviously Clipper is Alive & Well : -)

TIA & Enjoy ! (10th October 2012, 11:05; 13th November 2015)

Original Welcome Page for Clipper... Clipper... Clipper

This is the original Welcome Page for Clipper... Clipper... Clipper, which I am republishing for historical and sentimental reasons. The only changes that I have made was to fix all the broken links. BTW, the counter from is still working :-)

Welcome to Chee Chong Hwa's Malaysian WWW web site which is dedicated to Clipperheads throughout the world.

This site started out as a teeny-weeny section of Who the heck is Chee Chong Hwa ? and has graduated into a full blown web site of more than 140 pages (actually hundreds of A4 size pages) ! This is due to its growing popularity and tremendous encouragements from visiting Clipperheads from 100 countries worldwide, from North America, Central America, Caribbean, South America, Europe, Middle-East, Africa and Asia-Pacific. Thanx Clipperheads, you all made this happen !

What is Clipper ?

You may ask, what is this Clipper stuff ? Could Clipper be something to do with sailing as it is the name of a very fast sailing American ship in the 19th century ?

Well, Clipper or to be precise, CA-Clipper is the premier PC-Software development tool for DOS. It was first developed by Nantucket Corporation initially as a compiler for dBase3+ programs. Since then, CA-Clipper has evolved away from its x-base roots with the introduction of lexical scoping & pre-defined objects like TBrowse. As at today, the most stable version ofClipper is 5.2e while the latest version, 5.3a was introduced on 21 May 1996.

As at 11th November, 1996, an unofficial 5.3a fixes file was made available by Jo French. See the About CA-Clipper 5.3a section for more details. BTW, Jo French uploaded the revised 5.3a fixes file on 20th November, 1996.

Latest News

The latest news is that CA has finally released the long-awaited 5.3b patch on 21 May, 1997.

For 5.3b users, you must a take a look at Jo French's comments on unfixed bugs in 5.3b.

BTW, have you used Click ? If you're a serious Clipperprogrammer and need an excellent code formatter, Click is a natural choice. How to get it ? Simple, access Phil Barnett's site via my Cool Clipper Sites.

32-bits Clipper for Windows ?

Have you tried Xbase ++ ? Well, I have and compared to Delphi (my current Windows programming tool of choice), I'm still sticking to Delphi.

Anyway, you should visit the Alaska Home Page. Give it a chance and then draw your own conclusions !.

The Harbour Project

Is this the future of Xbase ? Take a look at at the Harbour Project

You are Visitor # ...

According to, you are visitor since 3 June 1996.

If you like or dislike what you see on this website, please drop me a line by clicking the email button at the bottom of this page or better still, by filling out the form in my guest book. If you are not sure what to write,click here to take a look at what other Clipperheads have to say.