<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
imperative	B-Application
programming	I-Application
is	O
a	O
programming	O
paradigm	O
of	O
software	O
that	O
uses	O
statements	O
that	O
change	O
a	O
program	O
's	O
state	B-Application
.	O
</s>
<s>
In	O
much	O
the	O
same	O
way	O
that	O
the	O
imperative	B-Application
mood	O
in	O
natural	O
languages	O
expresses	O
commands	O
,	O
an	O
imperative	B-Application
program	I-Application
consists	O
of	O
commands	O
for	O
the	O
computer	O
to	O
perform	O
.	O
</s>
<s>
Imperative	B-Application
programming	I-Application
focuses	O
on	O
describing	O
how	O
a	O
program	O
operates	O
step	O
by	O
step	O
,	O
rather	O
than	O
on	O
high-level	O
descriptions	O
of	O
its	O
expected	O
results	O
.	O
</s>
<s>
The	O
term	O
is	O
often	O
used	O
in	O
contrast	O
to	O
declarative	B-Language
programming	I-Language
,	O
which	O
focuses	O
on	O
what	O
the	O
program	O
should	O
accomplish	O
without	O
specifying	O
all	O
the	O
details	O
of	O
how	O
the	O
program	O
should	O
achieve	O
the	O
result	O
.	O
</s>
<s>
Procedural	B-Application
programming	I-Application
is	O
a	O
type	O
of	O
imperative	B-Application
programming	I-Application
in	O
which	O
the	O
program	O
is	O
built	O
from	O
one	O
or	O
more	O
procedures	O
(	O
also	O
termed	O
subroutines	O
or	O
functions	O
)	O
.	O
</s>
<s>
The	O
terms	O
are	O
often	O
used	O
as	O
synonyms	O
,	O
but	O
the	O
use	O
of	O
procedures	O
has	O
a	O
dramatic	O
effect	O
on	O
how	O
imperative	B-Application
programs	I-Application
appear	O
and	O
how	O
they	O
are	O
constructed	O
.	O
</s>
<s>
Heavy	O
procedural	B-Application
programming	I-Application
,	O
in	O
which	O
state	B-Application
changes	O
are	O
localized	O
to	O
procedures	O
or	O
restricted	O
to	O
explicit	O
arguments	O
and	O
returns	O
from	O
procedures	O
,	O
is	O
a	O
form	O
of	O
structured	B-Language
programming	I-Language
.	O
</s>
<s>
Since	O
the	O
1960	O
’s	O
,	O
structured	B-Language
programming	I-Language
and	O
modular	B-Architecture
programming	I-Architecture
in	O
general	O
have	O
been	O
promoted	O
as	O
techniques	O
to	O
improve	O
the	O
maintainability	O
and	O
overall	O
quality	O
of	O
imperative	B-Application
programs	I-Application
.	O
</s>
<s>
The	O
concepts	O
behind	O
object-oriented	B-Language
programming	I-Language
attempt	O
to	O
extend	O
this	O
approach	O
.	O
</s>
<s>
Procedural	B-Application
programming	I-Application
could	O
be	O
considered	O
a	O
step	O
toward	O
declarative	B-Language
programming	I-Language
.	O
</s>
<s>
At	O
the	O
same	O
time	O
,	O
a	O
complete	O
program	O
is	O
still	O
imperative	B-Application
since	O
it	O
fixes	O
the	O
statements	O
to	O
be	O
executed	O
and	O
their	O
order	O
of	O
execution	O
to	O
a	O
large	O
extent	O
.	O
</s>
<s>
The	O
programming	O
paradigm	O
used	O
to	O
build	O
programs	O
for	O
almost	O
all	O
computers	O
typically	O
follows	O
an	O
imperative	B-Application
model	O
.	O
</s>
<s>
Digital	O
computer	O
hardware	O
is	O
designed	O
to	O
execute	O
machine	B-Language
code	I-Language
,	O
which	O
is	O
native	O
to	O
the	O
computer	O
and	O
is	O
usually	O
written	O
in	O
the	O
imperative	B-Application
style	O
,	O
although	O
low-level	O
compilers	O
and	O
interpreters	O
using	O
other	O
paradigms	O
exist	O
for	O
some	O
architectures	O
such	O
as	O
lisp	B-Operating_System
machines	I-Operating_System
.	O
</s>
<s>
From	O
this	O
low-level	O
perspective	O
,	O
the	O
program	O
state	B-Application
is	O
defined	O
by	O
the	O
contents	O
of	O
memory	O
,	O
and	O
the	O
statements	O
are	O
instructions	O
in	O
the	O
native	O
machine	B-Language
language	I-Language
of	O
the	O
computer	O
.	O
</s>
<s>
Higher-level	O
imperative	B-Application
languages	I-Application
use	O
variables	O
and	O
more	O
complex	O
statements	O
,	O
but	O
still	O
follow	O
the	O
same	O
paradigm	O
.	O
</s>
<s>
Recipes	O
and	O
process	O
checklists	O
,	O
while	O
not	O
computer	B-Application
programs	I-Application
,	O
are	O
also	O
familiar	O
concepts	O
that	O
are	O
similar	O
in	O
style	O
to	O
imperative	B-Application
programming	I-Application
;	O
each	O
step	O
is	O
an	O
instruction	O
,	O
and	O
the	O
physical	O
world	O
holds	O
the	O
state	B-Application
.	O
</s>
<s>
Since	O
the	O
basic	O
ideas	O
of	O
imperative	B-Application
programming	I-Application
are	O
both	O
conceptually	O
familiar	O
and	O
directly	O
embodied	O
in	O
the	O
hardware	O
,	O
most	O
computer	O
languages	O
are	O
in	O
the	O
imperative	B-Application
style	O
.	O
</s>
<s>
Assignment	O
statements	O
,	O
in	O
imperative	B-Application
paradigm	I-Application
,	O
perform	O
an	O
operation	O
on	O
information	O
located	O
in	O
memory	O
and	O
store	O
the	O
results	O
in	O
memory	O
for	O
later	O
use	O
.	O
</s>
<s>
High-level	O
imperative	B-Application
languages	I-Application
,	O
in	O
addition	O
,	O
permit	O
the	O
evaluation	O
of	O
complex	O
expressions	O
,	O
which	O
may	O
consist	O
of	O
a	O
combination	O
of	O
arithmetic	O
operations	O
and	O
function	O
evaluations	O
,	O
and	O
the	O
assignment	O
of	O
the	O
resulting	O
value	O
to	O
memory	O
.	O
</s>
<s>
Looping	O
statements	O
(	O
as	O
in	O
while	O
loops	O
,	O
do	O
while	O
loops	O
,	O
and	O
for	B-Language
loops	I-Language
)	O
allow	O
a	O
sequence	O
of	O
statements	O
to	O
be	O
executed	O
multiple	O
times	O
.	O
</s>
<s>
Conditional	B-Language
branching	I-Language
statements	O
allow	O
a	O
sequence	O
of	O
statements	O
to	O
be	O
executed	O
only	O
if	O
some	O
condition	O
is	O
met	O
.	O
</s>
<s>
Unconditional	B-General_Concept
branching	I-General_Concept
statements	O
allow	O
an	O
execution	O
sequence	O
to	O
be	O
transferred	O
to	O
another	O
part	O
of	O
a	O
program	O
.	O
</s>
<s>
These	O
include	O
the	O
jump	O
(	O
called	O
goto	B-Application
in	O
many	O
languages	O
)	O
,	O
switch	O
,	O
and	O
the	O
subprogram	O
,	O
subroutine	O
,	O
or	O
procedure	O
call	O
(	O
which	O
usually	O
returns	O
to	O
the	O
next	O
statement	O
after	O
the	O
call	O
)	O
.	O
</s>
<s>
Early	O
in	O
the	O
development	O
of	O
high-level	B-Language
programming	I-Language
languages	I-Language
,	O
the	O
introduction	O
of	O
the	O
block	O
enabled	O
the	O
construction	O
of	O
programs	O
in	O
which	O
a	O
group	O
of	O
statements	O
and	O
declarations	O
could	O
be	O
treated	O
as	O
if	O
they	O
were	O
one	O
statement	O
.	O
</s>
<s>
This	O
,	O
alongside	O
the	O
introduction	O
of	O
subroutines	O
,	O
enabled	O
complex	O
structures	O
to	O
be	O
expressed	O
by	O
hierarchical	O
decomposition	O
into	O
simpler	O
procedural	B-Application
structures	O
.	O
</s>
<s>
Many	O
imperative	B-Application
programming	I-Application
languages	I-Application
(	O
such	O
as	O
Fortran	B-Application
,	O
BASIC	O
,	O
and	O
C	B-Language
)	O
are	O
abstractions	B-Application
of	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
The	O
earliest	O
imperative	B-Application
languages	I-Application
were	O
the	O
machine	B-Language
languages	I-Language
of	O
the	O
original	O
computers	O
.	O
</s>
<s>
FORTRAN	B-Application
,	O
developed	O
by	O
John	O
Backus	O
at	O
International	O
Business	O
Machines	O
(	O
IBM	O
)	O
starting	O
in	O
1954	O
,	O
was	O
the	O
first	O
major	O
programming	O
language	O
to	O
remove	O
the	O
obstacles	O
presented	O
by	O
machine	B-Language
code	I-Language
in	O
the	O
creation	O
of	O
complex	O
programs	O
.	O
</s>
<s>
FORTRAN	B-Application
was	O
a	O
compiled	B-Language
language	I-Language
that	O
allowed	O
named	O
variables	O
,	O
complex	O
expressions	O
,	O
subprograms	O
,	O
and	O
many	O
other	O
features	O
now	O
common	O
in	O
imperative	B-Application
languages	I-Application
.	O
</s>
<s>
The	O
next	O
two	O
decades	O
saw	O
the	O
development	O
of	O
many	O
other	O
major	O
high-level	O
imperative	B-Application
programming	I-Application
languages	I-Application
.	O
</s>
<s>
In	O
the	O
late	O
1950s	O
and	O
1960s	O
,	O
ALGOL	B-Language
was	O
developed	O
in	O
order	O
to	O
allow	O
mathematical	O
algorithms	O
to	O
be	O
more	O
easily	O
expressed	O
and	O
even	O
served	O
as	O
the	O
operating	B-General_Concept
system	I-General_Concept
's	O
target	O
language	O
for	O
some	O
computers	O
.	O
</s>
<s>
MUMPS	B-Language
(	O
1966	O
)	O
carried	O
the	O
imperative	B-Application
paradigm	I-Application
to	O
a	O
logical	O
extreme	O
,	O
by	O
not	O
having	O
any	O
statements	O
at	O
all	O
,	O
relying	O
purely	O
on	O
commands	O
,	O
even	O
to	O
the	O
extent	O
of	O
making	O
the	O
IF	O
and	O
ELSE	O
commands	O
independent	O
of	O
each	O
other	O
,	O
connected	O
only	O
by	O
an	O
intrinsic	O
variable	O
named	O
$TEST	O
.	O
</s>
<s>
COBOL	B-Application
(	O
1960	O
)	O
and	O
BASIC	O
(	O
1964	O
)	O
were	O
both	O
attempts	O
to	O
make	O
programming	O
syntax	O
look	O
more	O
like	O
English	O
.	O
</s>
<s>
In	O
the	O
1970s	O
,	O
Pascal	B-Application
was	O
developed	O
by	O
Niklaus	O
Wirth	O
,	O
and	O
C	B-Language
was	O
created	O
by	O
Dennis	O
Ritchie	O
while	O
he	O
was	O
working	O
at	O
Bell	O
Laboratories	O
.	O
</s>
<s>
Wirth	O
went	O
on	O
to	O
design	O
Modula-2	B-Language
and	O
Oberon	B-Language
.	O
</s>
<s>
For	O
the	O
needs	O
of	O
the	O
United	O
States	O
Department	O
of	O
Defense	O
,	O
Jean	O
Ichbiah	O
and	O
a	O
team	O
at	O
Honeywell	O
began	O
designing	O
Ada	B-Language
in	O
1978	O
,	O
after	O
a	O
4-year	O
project	O
to	O
define	O
the	O
requirements	O
for	O
the	O
language	O
.	O
</s>
<s>
The	O
1980s	O
saw	O
a	O
rapid	O
growth	O
in	O
interest	O
in	O
object-oriented	B-Language
programming	I-Language
.	O
</s>
<s>
These	O
languages	O
were	O
imperative	B-Application
in	O
style	O
,	O
but	O
added	O
features	O
to	O
support	O
objects	O
.	O
</s>
<s>
Smalltalk-80	B-Application
,	O
originally	O
conceived	O
by	O
Alan	O
Kay	O
in	O
1969	O
,	O
was	O
released	O
in	O
1980	O
,	O
by	O
the	O
Xerox	O
Palo	O
Alto	O
Research	O
Center	O
(	O
PARC	O
)	O
.	O
</s>
<s>
Drawing	O
from	O
concepts	O
in	O
another	O
object-oriented	B-Language
language	I-Language
—	O
Simula	B-Language
(	O
which	O
is	O
considered	O
the	O
world	O
's	O
first	O
object-oriented	B-Language
programming	I-Language
language	I-Language
,	O
developed	O
in	O
the	O
1960s	O
)	O
—	O
Bjarne	O
Stroustrup	O
designed	O
C++	B-Language
,	O
an	O
object-oriented	B-Language
language	I-Language
based	O
on	O
C	B-Language
.	O
Design	O
of	O
C++	B-Language
began	O
in	O
1979	O
and	O
the	O
first	O
implementation	O
was	O
completed	O
in	O
1983	O
.	O
</s>
<s>
In	O
the	O
late	O
1980s	O
and	O
1990s	O
,	O
the	O
notable	O
imperative	B-Application
languages	I-Application
drawing	O
on	O
object-oriented	B-Language
concepts	O
were	O
Perl	B-Language
,	O
released	O
by	O
Larry	O
Wall	O
in	O
1987	O
;	O
Python	B-Language
,	O
released	O
by	O
Guido	O
van	O
Rossum	O
in	O
1990	O
;	O
Visual	B-Language
Basic	I-Language
and	O
Visual	B-Application
C++	I-Application
(	O
which	O
included	O
Microsoft	B-Language
Foundation	I-Language
Class	I-Language
Library	I-Language
(	O
MFC	O
)	O
2.0	O
)	O
,	O
released	O
by	O
Microsoft	O
in	O
1991	O
and	O
1993	O
respectively	O
;	O
PHP	B-Application
,	O
released	O
by	O
Rasmus	O
Lerdorf	O
in	O
1994	O
;	O
Java	B-Language
,	O
by	O
James	O
Gosling	O
(	O
Sun	O
Microsystems	O
)	O
in	O
1995	O
,	O
JavaScript	B-Language
,	O
by	O
Brendan	O
Eich	O
(	O
Netscape	B-Protocol
)	O
,	O
and	O
Ruby	B-Language
,	O
by	O
Yukihiro	O
"	O
Matz	O
"	O
Matsumoto	O
,	O
both	O
released	O
in	O
1995	O
.	O
</s>
<s>
Microsoft	B-Application
's	I-Application
.NET	I-Application
Framework	I-Application
(	O
2002	O
)	O
is	O
imperative	B-Application
at	O
its	O
core	O
,	O
as	O
are	O
its	O
main	O
target	O
languages	O
,	O
VB.NET	B-Language
and	O
C#	B-Application
that	O
run	O
on	O
it	O
;	O
however	O
Microsoft	O
's	O
F#	B-Operating_System
,	O
a	O
functional	B-Language
language	I-Language
,	O
also	O
runs	O
on	O
it	O
.	O
</s>
<s>
FORTRAN	B-Application
(	O
1958	O
)	O
was	O
unveiled	O
as	O
"	O
The	O
IBM	O
Mathematical	O
FORmula	O
TRANslating	O
system.	O
"	O
</s>
<s>
However	O
,	O
non	O
IBM	O
vendors	O
also	O
wrote	O
Fortran	B-Application
compilers	O
,	O
but	O
with	O
a	O
syntax	O
that	O
would	O
likely	O
fail	O
IBM	O
's	O
compiler	O
.	O
</s>
<s>
The	O
American	O
National	O
Standards	O
Institute	O
(	O
ANSI	O
)	O
developed	O
the	O
first	O
Fortran	B-Application
standard	O
in	O
1966	O
.	O
</s>
<s>
In	O
1978	O
,	O
Fortran	B-Application
77	O
became	O
the	O
standard	O
until	O
1991	O
.	O
</s>
<s>
Fortran	B-Application
90	O
supports	O
:	O
</s>
<s>
COBOL	B-Application
(	O
1959	O
)	O
stands	O
for	O
"	O
COmmon	O
Business	O
Oriented	O
Language.	O
"	O
</s>
<s>
Fortran	B-Application
manipulated	O
symbols	O
.	O
</s>
<s>
The	O
US	O
Department	O
of	O
Defense	O
influenced	O
COBOL	B-Application
's	O
development	O
,	O
with	O
Grace	O
Hopper	O
being	O
a	O
major	O
contributor	O
.	O
</s>
<s>
COBOL	B-Application
's	O
development	O
was	O
tightly	O
controlled	O
,	O
so	O
dialects	O
did	O
n't	O
emerge	O
to	O
require	O
ANSI	O
standards	O
.	O
</s>
<s>
The	O
1990s	O
version	O
did	O
make	O
consequential	O
changes	O
,	O
like	O
object-oriented	B-Language
programming	I-Language
.	O
</s>
<s>
ALGOL	B-Language
(	O
1960	O
)	O
stands	O
for	O
"	O
ALGOrithmic	O
Language.	O
"	O
</s>
<s>
Algol	B-Language
was	O
first	O
to	O
define	O
its	O
syntax	O
using	O
the	O
Backus	O
–	O
Naur	O
form	O
.	O
</s>
<s>
This	O
led	O
to	O
syntax-directed	B-Application
compilers	O
.	O
</s>
<s>
Algol	B-Language
's	O
direct	O
descendants	O
include	O
Pascal	B-Application
,	O
Modula-2	B-Language
,	O
Ada	B-Language
,	O
Delphi	B-Language
and	O
Oberon	B-Language
on	O
one	O
branch	O
.	O
</s>
<s>
On	O
another	O
branch	O
there	O
's	O
C	B-Language
,	O
C++	B-Language
and	O
Java	B-Language
.	O
</s>
<s>
A	O
Basic	O
interpreter	O
was	O
installed	O
in	O
the	O
microcomputers	B-Architecture
manufactured	O
in	O
the	O
late	O
1970s	O
.	O
</s>
<s>
As	O
the	O
microcomputer	B-Architecture
industry	O
grew	O
,	O
so	O
did	O
the	O
language	O
.	O
</s>
<s>
Basic	O
pioneered	O
the	O
interactive	B-Application
session	I-Application
.	O
</s>
<s>
It	O
offered	O
operating	B-General_Concept
system	I-General_Concept
commands	O
within	O
its	O
environment	O
:	O
</s>
<s>
Recent	O
dialects	O
added	O
structure	O
and	O
object-oriented	B-Language
extensions	O
.	O
</s>
<s>
Microsoft	O
's	O
Visual	B-Language
Basic	I-Language
is	O
still	O
widely	O
used	O
and	O
produces	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
C	B-Language
programming	I-Language
language	I-Language
(	O
1973	O
)	O
got	O
its	O
name	O
because	O
the	O
language	O
BCPL	B-Language
was	O
replaced	O
with	O
B	B-Language
,	O
and	O
AT&T	O
Bell	O
Labs	O
called	O
the	O
next	O
version	O
"	O
C.	O
"	O
Its	O
purpose	O
was	O
to	O
write	O
the	O
UNIX	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
C	B-Language
is	O
a	O
relatively	O
small	O
language	O
--	O
making	O
it	O
easy	O
to	O
write	O
compilers	O
.	O
</s>
<s>
Its	O
growth	O
also	O
was	O
because	O
it	O
has	O
the	O
facilities	O
of	O
assembly	B-Language
language	I-Language
,	O
but	O
uses	O
a	O
high-level	B-Language
syntax	I-Language
.	O
</s>
<s>
C	B-Language
allows	O
the	O
programmer	O
to	O
control	O
which	O
region	O
of	O
memory	O
data	O
is	O
to	O
be	O
stored	O
.	O
</s>
<s>
The	O
stack	B-General_Concept
is	O
automatically	O
used	O
for	O
the	O
standard	O
variable	O
declarations	O
.	O
</s>
<s>
Heap	B-Application
memory	O
is	O
returned	O
to	O
a	O
pointer	O
variable	O
from	O
the	O
malloc( )	O
function	O
.	O
</s>
<s>
It	O
's	O
where	O
machine	B-Language
instructions	I-Language
are	O
stored	O
.	O
)	O
</s>
<s>
One	O
region	O
is	O
called	O
the	O
initialized	O
data	B-General_Concept
segment	I-General_Concept
,	O
where	O
variables	O
declared	O
with	O
default	O
values	O
are	O
stored	O
.	O
</s>
<s>
The	O
other	O
region	O
is	O
called	O
the	O
block	B-General_Concept
started	I-General_Concept
by	I-General_Concept
segment	I-General_Concept
,	O
where	O
variables	O
declared	O
without	O
default	O
values	O
are	O
stored	O
.	O
</s>
<s>
Variables	O
stored	O
in	O
the	O
global	O
and	O
static	O
data	O
region	O
have	O
their	O
addresses	B-General_Concept
set	O
at	O
compile-time	O
.	O
</s>
<s>
They	O
provide	O
an	O
interface	B-Application
to	O
the	O
function	O
.	O
</s>
<s>
The	O
stack	B-General_Concept
region	O
is	O
a	O
contiguous	O
block	O
of	O
memory	O
located	O
near	O
the	O
top	O
memory	B-General_Concept
address	I-General_Concept
.	O
</s>
<s>
Variables	O
placed	O
in	O
the	O
stack	B-General_Concept
,	O
ironically	O
,	O
are	O
populated	O
from	O
top	O
to	O
bottom	O
.	O
</s>
<s>
A	O
stack	B-General_Concept
pointer	O
is	O
a	O
special-purpose	O
register	B-General_Concept
that	O
keeps	O
track	O
of	O
the	O
last	O
memory	B-General_Concept
address	I-General_Concept
populated	O
.	O
</s>
<s>
Variables	O
are	O
placed	O
into	O
the	O
stack	B-General_Concept
via	O
the	O
assembly	B-Language
language	I-Language
PUSH	O
instruction	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
addresses	B-General_Concept
of	O
these	O
variables	O
are	O
set	O
during	O
runtime	B-Library
.	O
</s>
<s>
The	O
method	B-Language
for	O
stack	B-General_Concept
variables	O
to	O
lose	O
their	O
scope	B-Language
is	O
via	O
the	O
POP	O
instruction	O
.	O
</s>
<s>
Local	O
variables	O
declared	O
without	O
the	O
static	O
prefix	O
,	O
including	O
formal	O
parameter	O
variables	O
,	O
are	O
called	O
automatic	O
variables	O
and	O
are	O
stored	O
in	O
the	O
stack	B-General_Concept
.	O
</s>
<s>
They	O
are	O
visible	O
inside	O
the	O
function	O
or	O
block	O
and	O
lose	O
their	O
scope	B-Language
upon	O
exiting	O
the	O
function	O
or	O
block	O
.	O
</s>
<s>
The	O
heap	B-Application
region	O
is	O
located	O
below	O
the	O
stack	B-General_Concept
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
manages	O
the	O
heap	B-Application
using	O
a	O
heap	B-Application
pointer	O
and	O
a	O
list	O
of	O
allocated	O
memory	O
blocks	O
.	O
</s>
<s>
Like	O
the	O
stack	B-General_Concept
,	O
the	O
addresses	B-General_Concept
of	O
heap	B-Application
variables	O
are	O
set	O
during	O
runtime	B-Library
.	O
</s>
<s>
An	O
out	B-General_Concept
of	I-General_Concept
memory	I-General_Concept
error	O
occurs	O
when	O
the	O
heap	B-Application
pointer	O
and	O
the	O
stack	B-General_Concept
pointer	O
meet	O
.	O
</s>
<s>
C	B-Language
provides	O
the	O
malloc( )	O
library	O
function	O
to	O
allocate	B-Language
heap	B-Application
memory	O
.	O
</s>
<s>
Populating	O
the	O
heap	B-Application
with	O
data	O
is	O
an	O
additional	O
copy	O
function	O
.	O
</s>
<s>
Variables	O
stored	O
in	O
the	O
heap	B-Application
are	O
economically	O
passed	O
to	O
functions	O
using	O
pointers	O
.	O
</s>
<s>
Without	O
pointers	O
,	O
the	O
entire	O
block	O
of	O
data	O
would	O
have	O
to	O
be	O
passed	O
to	O
the	O
function	O
via	O
the	O
stack	B-General_Concept
.	O
</s>
<s>
In	O
the	O
1970s	O
,	O
software	B-General_Concept
engineers	I-General_Concept
needed	O
language	O
support	O
to	O
break	O
large	O
projects	O
down	O
into	O
modules	B-Architecture
.	O
</s>
<s>
One	O
obvious	O
feature	O
was	O
to	O
decompose	O
large	O
projects	O
physically	O
into	O
separate	O
files	B-Operating_System
.	O
</s>
<s>
At	O
the	O
time	O
,	O
languages	O
supported	O
concrete	O
(	O
scalar	O
)	O
datatypes	O
like	O
integer	O
numbers	O
,	O
floating-point	B-Algorithm
numbers	I-Algorithm
,	O
and	O
strings	O
of	O
characters	O
.	O
</s>
<s>
In	O
object-oriented	B-Language
jargon	O
,	O
abstract	O
datatypes	O
are	O
called	O
classes	O
.	O
</s>
<s>
Object-oriented	B-Language
imperative	I-Language
languages	I-Language
developed	O
by	O
combining	O
the	O
need	O
for	O
classes	O
and	O
the	O
need	O
for	O
safe	O
functional	B-Language
programming	I-Language
.	O
</s>
<s>
A	O
function	O
,	O
in	O
an	O
object-oriented	B-Language
language	I-Language
,	O
is	O
assigned	O
to	O
a	O
class	O
.	O
</s>
<s>
An	O
assigned	O
function	O
is	O
then	O
referred	O
to	O
as	O
a	O
method	B-Language
,	O
member	O
function	O
,	O
or	O
operation	O
.	O
</s>
<s>
Object-oriented	B-Language
programming	I-Language
is	O
executing	O
operations	O
on	O
objects	O
.	O
</s>
<s>
Object-oriented	B-Language
languages	I-Language
support	O
a	O
syntax	O
to	O
model	O
subset/superset	O
relationships	O
.	O
</s>
<s>
Object-oriented	B-Language
languages	I-Language
model	O
subset/superset	O
relationships	O
using	O
inheritance	B-Language
.	O
</s>
<s>
Object-oriented	B-Language
programming	I-Language
became	O
the	O
dominant	O
language	O
paradigm	O
by	O
the	O
late	O
1990s	O
.	O
</s>
<s>
C++	B-Language
(	O
1985	O
)	O
was	O
originally	O
called	O
"	O
C	B-Language
with	O
Classes.	O
"	O
</s>
<s>
It	O
was	O
designed	O
to	O
expand	O
C	B-Language
's	I-Language
capabilities	O
by	O
adding	O
the	O
object-oriented	B-Language
facilities	O
of	O
the	O
language	O
Simula	B-Language
.	O
</s>
<s>
An	O
object-oriented	B-Language
module	B-Architecture
is	O
composed	O
of	O
two	O
files	B-Operating_System
.	O
</s>
<s>
The	O
definitions	O
file	O
is	O
called	O
the	O
header	B-Language
file	I-Language
.	O
</s>
<s>
Here	O
is	O
a	O
C++	B-Language
header	B-Language
file	I-Language
for	O
the	O
GRADE	O
class	O
in	O
a	O
simple	O
school	O
application	O
:	O
</s>
<s>
A	O
module	B-Architecture
's	O
other	O
file	O
is	O
the	O
source	O
file	O
.	O
</s>
<s>
Here	O
is	O
a	O
C++	B-Language
source	O
file	O
for	O
the	O
GRADE	O
class	O
in	O
a	O
simple	O
school	O
application	O
:	O
</s>
<s>
Here	O
is	O
a	O
C++	B-Language
header	B-Language
file	I-Language
for	O
the	O
PERSON	O
class	O
in	O
a	O
simple	O
school	O
application	O
:	O
</s>
<s>
Here	O
is	O
a	O
C++	B-Language
source	O
file	O
for	O
the	O
PERSON	O
class	O
in	O
a	O
simple	O
school	O
application	O
:	O
</s>
<s>
Here	O
is	O
a	O
C++	B-Language
header	B-Language
file	I-Language
for	O
the	O
STUDENT	O
class	O
in	O
a	O
simple	O
school	O
application	O
:	O
</s>
<s>
Here	O
is	O
a	O
C++	B-Language
source	O
file	O
for	O
the	O
STUDENT	O
class	O
in	O
a	O
simple	O
school	O
application	O
:	O
</s>
