<s>
Computer	B-General_Concept
programming	I-General_Concept
is	O
the	O
process	O
of	O
performing	O
particular	O
computations	O
(	O
or	O
more	O
generally	O
,	O
accomplishing	O
specific	O
computing	O
results	O
)	O
,	O
usually	O
by	O
designing	O
and	O
building	O
executable	B-Application
computer	B-Application
programs	I-Application
.	O
</s>
<s>
The	O
source	O
code	O
of	O
a	O
program	O
is	O
written	O
in	O
one	O
or	O
more	O
languages	O
that	O
are	O
intelligible	O
to	O
programmers	B-Application
,	O
rather	O
than	O
machine	B-Language
code	I-Language
,	O
which	O
is	O
directly	O
executed	O
by	O
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
.	O
</s>
<s>
The	O
purpose	O
of	O
programming	O
is	O
to	O
find	O
a	O
sequence	O
of	O
instructions	O
that	O
will	O
automate	O
the	O
performance	B-General_Concept
of	O
a	O
task	O
(	O
which	O
can	O
be	O
as	O
complex	O
as	O
an	O
operating	B-General_Concept
system	I-General_Concept
)	O
on	O
a	O
computer	O
,	O
often	O
for	O
solving	O
a	O
given	O
problem	O
.	O
</s>
<s>
Proficient	O
programming	O
thus	O
usually	O
requires	O
expertise	O
in	O
several	O
different	O
subjects	O
,	O
including	O
knowledge	O
of	O
the	O
application	B-General_Concept
domain	I-General_Concept
,	O
specialized	O
algorithms	O
,	O
and	O
formal	O
logic	O
.	O
</s>
<s>
Tasks	O
accompanying	O
and	O
related	O
to	O
programming	O
include	O
testing	O
,	O
debugging	O
,	O
source	O
code	O
maintenance	O
,	O
implementation	O
of	O
build	B-Application
systems	I-Application
,	O
and	O
management	O
of	O
derived	O
artifacts	O
,	O
such	O
as	O
the	O
machine	B-Language
code	I-Language
of	O
computer	B-Application
programs	I-Application
.	O
</s>
<s>
Software	B-General_Concept
engineering	I-General_Concept
combines	O
engineering	O
techniques	O
and	O
principles	O
with	O
software	O
development	O
.	O
</s>
<s>
Programmable	B-General_Concept
devices	I-General_Concept
have	O
existed	O
for	O
centuries	O
.	O
</s>
<s>
In	O
1206	O
,	O
the	O
Arab	O
engineer	O
Al-Jazari	O
invented	O
a	O
programmable	O
drum	O
machine	O
where	O
a	O
musical	O
mechanical	O
automaton	O
could	O
be	O
made	O
to	O
play	O
different	O
rhythms	O
and	O
drum	O
patterns	O
,	O
via	O
pegs	O
and	O
cams	B-Data_Structure
.	O
</s>
<s>
The	O
first	O
computer	B-Application
program	I-Application
is	O
generally	O
dated	O
to	O
1843	O
,	O
when	O
mathematician	O
Ada	B-General_Concept
Lovelace	I-General_Concept
published	O
an	O
algorithm	O
to	O
calculate	O
a	O
sequence	O
of	O
Bernoulli	O
numbers	O
,	O
intended	O
to	O
be	O
carried	O
out	O
by	O
Charles	O
Babbage	O
's	O
Analytical	B-Device
Engine	I-Device
.	O
</s>
<s>
Later	O
a	O
control	O
panel	O
(	O
plug	O
board	O
)	O
added	O
to	O
his	O
1906	O
Type	O
I	O
Tabulator	O
allowed	O
it	O
to	O
be	O
programmed	O
for	O
different	O
jobs	O
,	O
and	O
by	O
the	O
late	O
1940s	O
,	O
unit	O
record	O
equipment	O
such	O
as	O
the	O
IBM	O
602	O
and	O
IBM	B-Device
604	I-Device
,	O
were	O
programmed	O
by	O
control	O
panels	O
in	O
a	O
similar	O
way	O
,	O
as	O
were	O
the	O
first	O
electronic	O
computers	O
.	O
</s>
<s>
However	O
,	O
with	O
the	O
concept	O
of	O
the	O
stored-program	O
computer	O
introduced	O
in	O
1949	O
,	O
both	O
programs	O
and	O
data	O
were	O
stored	O
and	O
manipulated	O
in	O
the	O
same	O
way	O
in	O
computer	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
Machine	B-Language
code	I-Language
was	O
the	O
language	O
of	O
early	O
programs	O
,	O
written	O
in	O
the	O
instruction	B-General_Concept
set	I-General_Concept
of	O
the	O
particular	O
machine	O
,	O
often	O
in	O
binary	O
notation	O
.	O
</s>
<s>
Assembly	B-Language
languages	I-Language
were	O
soon	O
developed	O
that	O
let	O
the	O
programmer	B-Application
specify	O
instruction	O
in	O
a	O
text	O
format	O
(	O
e.g.	O
,	O
ADD	O
X	O
,	O
TOTAL	O
)	O
,	O
with	O
abbreviations	O
for	O
each	O
operation	O
code	O
and	O
meaningful	O
names	O
for	O
specifying	O
addresses	O
.	O
</s>
<s>
However	O
,	O
because	O
an	O
assembly	B-Language
language	I-Language
is	O
little	O
more	O
than	O
a	O
different	O
notation	O
for	O
a	O
machine	B-Language
language	I-Language
,	O
two	O
machines	O
with	O
different	B-Architecture
instruction	I-Architecture
sets	I-Architecture
also	O
have	O
different	O
assembly	B-Language
languages	I-Language
.	O
</s>
<s>
High-level	B-Language
languages	I-Language
made	O
the	O
process	O
of	O
developing	O
a	O
program	O
simpler	O
and	O
more	O
understandable	O
,	O
and	O
less	O
bound	O
to	O
the	O
underlying	O
hardware	B-Architecture
.	O
</s>
<s>
The	O
first	O
compiler	B-Language
related	O
tool	O
,	O
the	O
A-0	B-Language
System	I-Language
,	O
was	O
developed	O
in	O
1952	O
by	O
Grace	O
Hopper	O
,	O
who	O
also	O
coined	O
the	O
term	O
'	O
compiler	B-Language
 '	O
.	O
</s>
<s>
FORTRAN	B-Application
,	O
the	O
first	O
widely	O
used	O
high-level	B-Language
language	I-Language
to	O
have	O
a	O
functional	O
implementation	O
,	O
came	O
out	O
in	O
1957	O
,	O
and	O
many	O
other	O
languages	O
were	O
soon	O
developed	O
—	O
in	O
particular	O
,	O
COBOL	B-Application
aimed	O
at	O
commercial	O
data	O
processing	O
,	O
and	O
Lisp	B-Language
for	O
computer	O
research	O
.	O
</s>
<s>
These	O
compiled	B-Language
languages	O
allow	O
the	O
programmer	B-Application
to	O
write	O
programs	O
in	O
terms	O
that	O
are	O
syntactically	O
richer	O
,	O
and	O
more	O
capable	O
of	O
abstracting	B-Application
the	O
code	O
,	O
making	O
it	O
easy	O
to	O
target	O
varying	O
machine	B-Language
instruction	I-Language
sets	O
via	O
compilation	B-Language
declarations	O
and	O
heuristics	B-Algorithm
.	O
</s>
<s>
Compilers	B-Language
harnessed	O
the	O
power	O
of	O
computers	O
to	O
make	O
programming	O
easier	O
by	O
allowing	O
programmers	B-Application
to	O
specify	O
calculations	O
by	O
entering	O
a	O
formula	O
using	O
infix	O
notation	O
.	O
</s>
<s>
Programs	O
were	O
mostly	O
entered	O
using	O
punched	B-Architecture
cards	I-Architecture
or	O
paper	O
tape	O
.	O
</s>
<s>
By	O
the	O
late	O
1960s	O
,	O
data	B-General_Concept
storage	I-General_Concept
devices	I-General_Concept
and	O
computer	B-General_Concept
terminals	I-General_Concept
became	O
inexpensive	O
enough	O
that	O
programs	O
could	O
be	O
created	O
by	O
typing	O
directly	O
into	O
the	O
computers	O
.	O
</s>
<s>
Text	B-Application
editors	I-Application
were	O
also	O
developed	O
that	O
allowed	O
changes	O
and	O
corrections	O
to	O
be	O
made	O
much	O
more	O
easily	O
than	O
with	O
punched	B-Architecture
cards	I-Architecture
.	O
</s>
<s>
This	O
depends	O
on	O
conceptual	O
correctness	O
of	O
algorithms	O
and	O
minimization	O
of	O
programming	O
mistakes	O
,	O
such	O
as	O
mistakes	O
in	O
resource	O
management	O
(	O
e.g.	O
,	O
buffer	B-General_Concept
overflows	I-General_Concept
and	O
race	B-Operating_System
conditions	I-Operating_System
)	O
and	O
logic	O
errors	O
(	O
such	O
as	O
division	O
by	O
zero	O
or	O
off-by-one	B-Error_Name
errors	I-Error_Name
)	O
.	O
</s>
<s>
Robustness	B-Application
:	O
how	O
well	O
a	O
program	O
anticipates	O
problems	O
due	O
to	O
errors	O
(	O
not	O
bugs	B-Error_Name
)	O
.	O
</s>
<s>
This	O
includes	O
situations	O
such	O
as	O
incorrect	O
,	O
inappropriate	O
or	O
corrupt	O
data	O
,	O
unavailability	O
of	O
needed	O
resources	O
such	O
as	O
memory	O
,	O
operating	B-General_Concept
system	I-General_Concept
services	O
,	O
and	O
network	O
connections	O
,	O
user	O
error	O
,	O
and	O
unexpected	O
power	O
outages	O
.	O
</s>
<s>
Usability	B-General_Concept
:	O
the	O
ergonomics	O
of	O
a	O
program	O
:	O
the	O
ease	O
with	O
which	O
a	O
person	O
can	O
use	O
the	O
program	O
for	O
its	O
intended	O
purpose	O
or	O
in	O
some	O
cases	O
even	O
unanticipated	O
purposes	O
.	O
</s>
<s>
This	O
involves	O
a	O
wide	O
range	O
of	O
textual	O
,	O
graphical	O
,	O
and	O
sometimes	O
hardware	B-Architecture
elements	O
that	O
improve	O
the	O
clarity	O
,	O
intuitiveness	O
,	O
cohesiveness	O
and	O
completeness	O
of	O
a	O
program	O
's	O
user	O
interface	O
.	O
</s>
<s>
Portability	B-Architecture
:	O
the	O
range	O
of	O
computer	B-Architecture
hardware	I-Architecture
and	O
operating	B-General_Concept
system	I-General_Concept
platforms	O
on	O
which	O
the	O
source	O
code	O
of	O
a	O
program	O
can	O
be	O
compiled/interpreted	O
and	O
run	O
.	O
</s>
<s>
This	O
depends	O
on	O
differences	O
in	O
the	O
programming	O
facilities	O
provided	O
by	O
the	O
different	O
platforms	O
,	O
including	O
hardware	B-Architecture
and	O
operating	B-General_Concept
system	I-General_Concept
resources	O
,	O
expected	O
behavior	O
of	O
the	O
hardware	B-Architecture
and	O
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
availability	O
of	O
platform-specific	O
compilers	B-Language
(	O
and	O
sometimes	O
libraries	O
)	O
for	O
the	O
language	O
of	O
the	O
source	O
code	O
.	O
</s>
<s>
Maintainability	O
:	O
the	O
ease	O
with	O
which	O
a	O
program	O
can	O
be	O
modified	O
by	O
its	O
present	O
or	O
future	O
developers	B-Application
in	O
order	O
to	O
make	O
improvements	O
or	O
to	O
customize	O
,	O
fix	O
bugs	B-Error_Name
and	O
security	O
holes	O
,	O
or	O
adapt	O
it	O
to	O
new	O
environments	O
.	O
</s>
<s>
Efficiency/performance	O
:	O
Measure	O
of	O
system	O
resources	O
a	O
program	O
consumes	O
(	O
processor	O
time	O
,	O
memory	O
space	O
,	O
slow	O
devices	O
such	O
as	O
disks	O
,	O
network	O
bandwidth	O
and	O
to	O
some	O
extent	O
even	O
user	O
interaction	O
)	O
:	O
the	O
less	O
,	O
the	O
better	O
.	O
</s>
<s>
This	O
also	O
includes	O
careful	O
management	O
of	O
resources	O
,	O
for	O
example	O
cleaning	O
up	O
temporary	B-Application
files	I-Application
and	O
eliminating	O
memory	B-Error_Name
leaks	I-Error_Name
.	O
</s>
<s>
Although	O
the	O
language	O
certainly	O
affects	O
performance	B-General_Concept
,	O
even	O
slower	O
languages	O
,	O
such	O
as	O
Python	B-Language
,	O
can	O
execute	O
programs	O
instantly	O
from	O
a	O
human	O
perspective	O
.	O
</s>
<s>
Speed	O
,	O
resource	O
usage	O
,	O
and	O
performance	B-General_Concept
are	O
important	O
for	O
programs	O
that	O
bottleneck	O
the	O
system	O
,	O
but	O
efficient	O
use	O
of	O
programmer	B-Application
time	O
is	O
also	O
important	O
and	O
is	O
related	O
to	O
cost	O
:	O
more	O
hardware	B-Architecture
may	O
be	O
cheaper	O
.	O
</s>
<s>
In	O
computer	B-General_Concept
programming	I-General_Concept
,	O
readability	O
refers	O
to	O
the	O
ease	O
with	O
which	O
a	O
human	O
reader	O
can	O
comprehend	O
the	O
purpose	O
,	O
control	O
flow	O
,	O
and	O
operation	O
of	O
source	O
code	O
.	O
</s>
<s>
It	O
affects	O
the	O
aspects	O
of	O
quality	O
above	O
,	O
including	O
portability	B-Architecture
,	O
usability	B-General_Concept
and	O
most	O
importantly	O
maintainability	O
.	O
</s>
<s>
Readability	O
is	O
important	O
because	O
programmers	B-Application
spend	O
the	O
majority	O
of	O
their	O
time	O
reading	O
,	O
trying	O
to	O
understand	O
,	O
reusing	O
and	O
modifying	O
existing	O
source	O
code	O
,	O
rather	O
than	O
writing	O
new	O
source	O
code	O
.	O
</s>
<s>
Unreadable	O
code	O
often	O
leads	O
to	O
bugs	B-Error_Name
,	O
inefficiencies	O
,	O
and	O
duplicated	O
code	O
.	O
</s>
<s>
Following	O
a	O
consistent	O
programming	B-Language
style	I-Language
often	O
helps	O
readability	O
.	O
</s>
<s>
However	O
,	O
readability	O
is	O
more	O
than	O
just	O
programming	B-Language
style	I-Language
.	O
</s>
<s>
Many	O
factors	O
,	O
having	O
little	O
or	O
nothing	O
to	O
do	O
with	O
the	O
ability	O
of	O
the	O
computer	O
to	O
efficiently	O
compile	B-Language
and	O
execute	O
the	O
code	O
,	O
contribute	O
to	O
readability	O
.	O
</s>
<s>
The	O
presentation	O
aspects	O
of	O
this	O
(	O
such	O
as	O
indents	O
,	O
line	O
breaks	O
,	O
color	O
highlighting	O
,	O
and	O
so	O
on	O
)	O
are	O
often	O
handled	O
by	O
the	O
source	B-Application
code	I-Application
editor	I-Application
,	O
but	O
the	O
content	O
aspects	O
reflect	O
the	O
programmer	B-Application
's	O
talent	O
and	O
skills	O
.	O
</s>
<s>
Various	O
visual	B-Language
programming	I-Language
languages	I-Language
have	O
also	O
been	O
developed	O
with	O
the	O
intent	O
to	O
resolve	O
readability	O
concerns	O
by	O
adopting	O
non-traditional	O
approaches	O
to	O
code	O
structure	O
and	O
display	O
.	O
</s>
<s>
Integrated	B-Application
development	I-Application
environments	I-Application
(	O
IDEs	O
)	O
aim	O
to	O
integrate	O
all	O
such	O
help	O
.	O
</s>
<s>
The	O
academic	O
field	O
and	O
the	O
engineering	O
practice	O
of	O
computer	B-General_Concept
programming	I-General_Concept
are	O
both	O
largely	O
concerned	O
with	O
discovering	O
and	O
implementing	O
the	O
most	O
efficient	B-General_Concept
algorithms	I-General_Concept
for	O
a	O
given	O
class	O
of	O
problems	O
.	O
</s>
<s>
Expert	O
programmers	B-Application
are	O
familiar	O
with	O
a	O
variety	O
of	O
well-established	O
algorithms	O
and	O
their	O
respective	O
complexities	O
and	O
use	O
this	O
knowledge	O
to	O
choose	O
algorithms	O
that	O
are	O
best	O
suited	O
to	O
the	O
circumstances	O
.	O
</s>
<s>
One	O
approach	O
popular	O
for	O
requirements	O
analysis	O
is	O
Use	B-Architecture
Case	I-Architecture
analysis	O
.	O
</s>
<s>
Many	O
programmers	B-Application
use	O
forms	O
of	O
Agile	O
software	O
development	O
where	O
the	O
various	O
stages	O
of	O
formal	O
software	O
development	O
are	O
more	O
integrated	O
together	O
into	O
short	O
cycles	O
that	O
take	O
a	O
few	O
weeks	O
rather	O
than	O
years	O
.	O
</s>
<s>
Popular	O
modeling	O
techniques	O
include	O
Object-Oriented	B-Application
Analysis	I-Application
and	I-Application
Design	I-Application
(	O
OOAD	B-Application
)	O
and	O
Model-Driven	B-Architecture
Architecture	I-Architecture
(	O
MDA	B-Architecture
)	O
.	O
</s>
<s>
The	O
Unified	B-Language
Modeling	I-Language
Language	I-Language
(	O
UML	B-Language
)	O
is	O
a	O
notation	O
used	O
for	O
both	O
the	O
OOAD	B-Application
and	O
MDA	B-Architecture
.	O
</s>
<s>
A	O
similar	O
technique	O
used	O
for	O
database	O
design	O
is	O
Entity-Relationship	B-Architecture
Modeling	O
(	O
ER	B-Architecture
Modeling	I-Architecture
)	O
.	O
</s>
<s>
Implementation	O
techniques	O
include	O
imperative	O
languages	O
(	O
object-oriented	B-Language
or	O
procedural	B-Application
)	O
,	O
functional	B-Language
languages	I-Language
,	O
and	O
logic	B-Language
languages	I-Language
.	O
</s>
<s>
Methods	O
of	O
measuring	O
programming	O
language	O
popularity	O
include	O
:	O
counting	O
the	O
number	O
of	O
job	O
advertisements	O
that	O
mention	O
the	O
language	O
,	O
the	O
number	O
of	O
books	O
sold	O
and	O
courses	O
teaching	O
the	O
language	O
(	O
this	O
overestimates	O
the	O
importance	O
of	O
newer	O
languages	O
)	O
,	O
and	O
estimates	O
of	O
the	O
number	O
of	O
existing	O
lines	O
of	O
code	O
written	O
in	O
the	O
language	O
(	O
this	O
underestimates	O
the	O
number	O
of	O
users	O
of	O
business	O
languages	O
such	O
as	O
COBOL	B-Application
)	O
.	O
</s>
<s>
For	O
example	O
,	O
COBOL	B-Application
is	O
still	O
strong	O
in	O
corporate	O
data	O
centers	O
often	O
on	O
large	O
mainframe	B-Architecture
computers	I-Architecture
,	O
Fortran	B-Application
in	O
engineering	O
applications	O
,	O
scripting	B-Language
languages	I-Language
in	O
Web	O
development	O
,	O
and	O
C	B-Language
in	O
embedded	B-Application
software	I-Application
.	O
</s>
<s>
New	O
languages	O
are	O
generally	O
designed	O
around	O
the	O
syntax	O
of	O
a	O
prior	O
language	O
with	O
new	O
functionality	O
added	O
,	O
(	O
for	O
example	O
C++	B-Language
adds	O
object-orientation	O
to	O
C	B-Language
,	O
and	O
Java	B-Language
adds	O
memory	O
management	O
and	O
bytecode	O
to	O
C++	B-Language
,	O
but	O
as	O
a	O
result	O
,	O
loses	O
efficiency	B-General_Concept
and	O
the	O
ability	O
for	O
low-level	O
manipulation	O
)	O
.	O
</s>
<s>
Some	O
languages	O
are	O
more	O
prone	O
to	O
some	O
kinds	O
of	O
faults	O
because	O
their	O
specification	B-Application
does	O
not	O
require	O
compilers	B-Language
to	O
perform	O
as	O
much	O
checking	O
as	O
other	O
languages	O
.	O
</s>
<s>
This	O
can	O
be	O
a	O
non-trivial	O
task	O
,	O
for	O
example	O
as	O
with	O
parallel	O
processes	O
or	O
some	O
unusual	O
software	B-Error_Name
bugs	I-Error_Name
.	O
</s>
<s>
After	O
the	O
bug	B-Error_Name
is	O
reproduced	O
,	O
the	O
input	O
of	O
the	O
program	O
may	O
need	O
to	O
be	O
simplified	O
to	O
make	O
it	O
easier	O
to	O
debug	O
.	O
</s>
<s>
For	O
example	O
,	O
when	O
a	O
bug	B-Error_Name
in	O
a	O
compiler	B-Language
can	O
make	O
it	O
crash	O
when	O
parsing	B-Language
some	O
large	O
source	O
file	O
,	O
a	O
simplification	O
of	O
the	O
test	O
case	O
that	O
results	O
in	O
only	O
few	O
lines	O
from	O
the	O
original	O
source	O
file	O
can	O
be	O
sufficient	O
to	O
reproduce	O
the	O
same	O
crash	O
.	O
</s>
<s>
Trial-and-error/divide	O
-and-conquer	O
is	O
needed	O
:	O
the	O
programmer	B-Application
will	O
try	O
to	O
remove	O
some	O
parts	O
of	O
the	O
original	O
test	O
case	O
and	O
check	O
if	O
the	O
problem	O
still	O
exists	O
.	O
</s>
<s>
When	O
debugging	O
the	O
problem	O
in	O
a	O
GUI	O
,	O
the	O
programmer	B-Application
can	O
try	O
to	O
skip	O
some	O
user	O
interaction	O
from	O
the	O
original	O
problem	O
description	O
and	O
check	O
if	O
remaining	O
actions	O
are	O
sufficient	O
for	O
bugs	B-Error_Name
to	O
appear	O
.	O
</s>
<s>
Standalone	O
debuggers	O
like	O
GDB	B-Language
are	O
also	O
used	O
,	O
and	O
these	O
often	O
provide	O
less	O
of	O
a	O
visual	O
environment	O
,	O
usually	O
using	O
a	O
command	B-Application
line	I-Application
.	O
</s>
<s>
Some	O
text	B-Application
editors	I-Application
such	O
as	O
Emacs	B-Application
allow	O
GDB	B-Language
to	O
be	O
invoked	O
through	O
them	O
,	O
to	O
provide	O
a	O
visual	O
environment	O
.	O
</s>
<s>
Trade-offs	O
from	O
this	O
ideal	O
involve	O
finding	O
enough	O
programmers	B-Application
who	O
know	O
the	O
language	O
to	O
build	O
a	O
team	O
,	O
the	O
availability	O
of	O
compilers	B-Language
for	O
that	O
language	O
,	O
and	O
the	O
efficiency	B-General_Concept
with	O
which	O
programs	O
written	O
in	O
a	O
given	O
language	O
execute	O
.	O
</s>
<s>
Computer	B-Application
programmers	I-Application
are	O
those	O
who	O
write	O
computer	O
software	O
.	O
</s>
<s>
Although	O
programming	O
has	O
been	O
presented	O
in	O
the	O
media	O
as	O
a	O
somewhat	O
mathematical	O
subject	O
,	O
some	O
research	O
shows	O
that	O
good	O
programmers	B-Application
have	O
strong	O
skills	O
in	O
natural	O
human	O
languages	O
,	O
and	O
that	O
learning	O
to	O
code	O
is	O
similar	O
to	O
learning	O
a	O
foreign	O
language	O
.	O
</s>
