<s>
xHarbour	B-Language
is	O
a	O
free	B-Application
multi-platform	O
extended	O
Clipper	B-Application
compiler	O
,	O
offering	O
multiple	O
graphic	O
terminals	O
(	O
GTs	O
)	O
,	O
including	O
console	O
drivers	O
,	O
GUIs	O
,	O
and	O
hybrid	O
console/GUIs	O
.	O
</s>
<s>
xHarbour	B-Language
is	O
backward-compatible	O
with	O
Clipper	B-Application
and	O
supports	O
many	O
language	O
syntax	O
extensions	O
,	O
greatly	O
extended	O
run-time	O
libraries	O
,	O
and	O
extensive	O
third	O
party	O
support	O
.	O
</s>
<s>
Like	O
most	O
dynamic	O
languages	O
,	O
xHarbour	B-Language
is	O
also	O
available	O
as	O
a	O
scripting	O
language	O
(	O
standalone	O
application	O
,	O
linkable	O
library	O
,	O
MS	O
ActiveScript	O
engine	O
[	O
Windows	O
Script	O
Host	O
,	O
HTML	O
,	O
ASP ]	O
)	O
utilizing	O
an	O
interpreter	O
written	O
in	O
the	O
xHarbour	B-Language
language	O
.	O
</s>
<s>
The	O
xHarbour	B-Language
Usenet	B-Application
newsgroup	I-Application
is	O
an	O
active	O
community	O
for	O
discussing	O
xHarbour	B-Language
related	O
questions	O
.	O
</s>
<s>
xHarbour	B-Language
has	O
6	O
scalar	O
types	O
:	O
Nil	O
,	O
String	O
,	O
Date	O
,	O
Logical	O
,	O
Number	O
,	O
Pointer	O
,	O
and	O
4	O
complex	O
types	O
:	O
Array	O
,	O
Object	O
,	O
CodeBlock	O
,	O
and	O
Hash	B-Algorithm
.	O
</s>
<s>
Hashes	O
,	O
or	O
associative	B-Application
arrays	I-Application
,	O
are	O
unordered	O
collections	O
of	O
any	O
type	O
values	O
indexed	O
by	O
their	O
associated	O
key	O
,	O
which	O
may	O
be	O
of	O
any	O
scalar	O
or	O
complex	O
type	O
.	O
</s>
<s>
Hash	B-Algorithm
:	O
</s>
<s>
If	O
a	O
STATIC	O
variable	O
is	O
declared	O
before	O
any	O
Procedure/Function/Method	O
is	O
defined	O
,	O
it	O
has	O
a	O
MODULE	B-Application
scope	O
,	O
and	O
is	O
visible	O
within	O
any	O
routine	O
defined	O
within	O
that	O
same	O
source	O
file	O
,	O
it	O
will	O
maintain	O
its	O
life	O
for	O
the	O
duration	O
of	O
the	O
application	O
lifetime	O
.	O
</s>
<s>
GLOBAL	O
Visible	O
within	O
any	O
routine	O
defined	O
in	O
the	O
same	O
source	O
module	B-Application
where	O
the	O
GLOBAL	O
variable	O
is	O
declared	O
,	O
as	O
well	O
as	O
any	O
routine	O
of	O
any	O
other	O
source	O
module	B-Application
,	O
which	O
explicitly	O
declares	O
it	O
,	O
by	O
means	O
of	O
the	O
GLOBAL	O
EXTERNAL	O
declaration	O
.	O
</s>
<s>
LOCAL	O
,	O
STATIC	O
,	O
and	O
GLOBAL	O
are	O
resolved	O
at	O
compile	O
time	O
,	O
and	O
thus	O
are	O
much	O
faster	O
than	O
PRIVATE	O
and	O
PUBLIC	O
variables	O
which	O
are	O
dynamic	O
entities	O
accessed	O
by	O
means	O
of	O
a	O
runtime	O
Symbol	B-Application
table	I-Application
.	O
</s>
<s>
The	O
basic	O
control	O
structures	O
include	O
all	O
of	O
the	O
standard	O
dBase	B-Application
,	O
and	O
Clipper	B-Application
control	O
structures	O
as	O
well	O
as	O
additional	O
ones	O
inspired	O
by	O
the	O
C	B-Language
or	O
Java	B-Language
programming	I-Language
languages	I-Language
:	O
</s>
<s>
The	O
...	O
is	O
a	O
sequence	O
of	O
one	O
of	O
more	O
xHarbour	B-Language
statements	O
,	O
and	O
square	O
bracketes	O
denote	O
optional	O
syntax	O
.	O
</s>
<s>
The	O
collection	O
expression	O
,	O
may	O
be	O
an	O
Array	O
(	O
of	O
any	O
type	O
or	O
combinations	O
of	O
types	O
)	O
,	O
an	O
Hash	B-Algorithm
Table	I-Algorithm
,	O
or	O
an	O
Object	O
type	O
.	O
</s>
<s>
xHarbour	B-Language
supports	O
a	O
SWITCH	O
construct	O
inspired	O
by	O
the	O
C	B-Language
implementation	O
of	O
switch( )	O
.	O
</s>
<s>
The	O
EXIT	O
optional	O
statement	O
is	O
the	O
equivalent	O
of	O
the	O
C	B-Language
statement	O
break	O
,	O
and	O
if	O
present	O
,	O
execution	O
of	O
the	O
SWITCH	O
structure	O
will	O
end	O
when	O
the	O
EXIT	O
statement	O
is	O
reached	O
,	O
otherwise	O
it	O
will	O
continue	O
with	O
the	O
first	O
statement	O
below	O
the	O
next	O
CASE	O
statement	O
(	O
fall	O
through	O
)	O
.	O
</s>
<s>
Additionally	O
the	O
xHarbour	B-Language
Error	O
Object	O
supports	O
canDefault	O
,	O
canRetry	O
and	O
canSubstitute	O
properties	O
,	O
which	O
allows	O
error	O
handlers	O
to	O
perform	O
some	O
preparations	O
,	O
and	O
then	O
request	O
a	O
Retry	O
Operation	O
,	O
a	O
Resume	O
,	O
or	O
return	O
a	O
Value	O
to	O
replace	O
the	O
expression	O
triggering	O
the	O
error	O
condition	O
.	O
</s>
<s>
Procedures/Functions	O
in	O
xHarbour	B-Language
can	O
be	O
specified	O
with	O
the	O
keywords	O
PROCEDURE	O
,	O
or	O
FUNCTION	O
.	O
</s>
<s>
Both	O
Procedures	O
and	O
Functions	O
may	O
be	O
qualified	O
by	O
the	O
scope	O
qualifier	O
STATIC	O
to	O
restrict	O
their	O
usage	O
to	O
the	O
scope	O
of	O
the	O
module	B-Application
where	O
defined	O
.	O
</s>
<s>
xHarbour	B-Language
extends	O
the	O
Clipper	B-Application
Replaceable	O
Database	O
Drivers	O
(	O
RDD	O
)	O
approach	O
.	O
</s>
<s>
In	O
xHarbour	B-Language
multiple	O
RDDs	O
can	O
be	O
used	O
in	O
a	O
single	O
application	O
,	O
and	O
new	O
logical	O
RDDs	O
can	O
be	O
defined	O
from	O
combination	O
of	O
other	O
RDD	O
.	O
</s>
<s>
xHarbour	B-Language
also	O
offers	O
ODBC	O
support	O
by	O
means	O
of	O
an	O
OOP	O
syntax	O
,	O
and	O
ADO	O
support	O
by	O
means	O
of	O
OLE	O
.	O
</s>
<s>
xHarbour	B-Language
’s	O
implementation	O
of	O
the	O
Macro	O
Operator	O
allows	O
for	O
runtime	O
compilation	O
of	O
any	O
valid	O
xHarbour	B-Language
expression	O
.	O
</s>
<s>
IOW	O
,	O
any	O
xHarbour	B-Language
application	O
may	O
be	O
extended	O
,	O
and/or	O
modified	O
in	O
runtime	O
,	O
to	O
compile	O
and	O
execute	O
additional	O
code	O
on	O
demand	O
.	O
</s>
<s>
The	O
xHarbour	B-Language
implementation	O
of	O
this	O
feature	O
is	O
so	O
complete	O
that	O
the	O
xHarbour	B-Language
interpreter	O
,	O
xbScript	O
,	O
uses	O
it	O
heavily	O
,	O
to	O
compile	O
xHarbour	B-Language
scripts	O
.	O
</s>
<s>
xHarbour	B-Language
is	O
also	O
available	O
as	O
an	O
interpreted	O
language	O
in	O
few	O
flavors	O
of	O
scripting	O
engines	O
.	O
</s>
