<s>
In	O
the	O
C++	B-Language
programming	I-Language
language	I-Language
,	O
the	O
C++	B-Language
Standard	B-Library
Library	I-Library
is	O
a	O
collection	O
of	O
classes	O
and	O
functions	O
,	O
which	O
are	O
written	O
in	O
the	O
core	O
language	O
and	O
part	O
of	O
the	O
C++	B-Language
ISO	O
Standard	O
itself	O
.	O
</s>
<s>
The	O
C++	B-Language
Standard	B-Library
Library	I-Library
provides	O
several	O
generic	O
containers	O
,	O
functions	O
to	O
use	O
and	O
manipulate	O
these	O
containers	O
,	O
function	B-Language
objects	I-Language
,	O
generic	O
strings	O
and	O
streams	O
(	O
including	O
interactive	O
and	O
file	O
I/O	O
)	O
,	O
support	O
for	O
some	O
language	O
features	O
,	O
and	O
functions	O
for	O
common	O
tasks	O
such	O
as	O
finding	O
the	O
square	O
root	O
of	O
a	O
number	O
.	O
</s>
<s>
The	O
C++	B-Language
Standard	B-Library
Library	I-Library
also	O
incorporates	O
most	O
headers	O
of	O
the	O
ISO	B-Language
C	I-Language
standard	I-Language
library	I-Language
ending	O
with	O
"	O
.h	O
"	O
,	O
but	O
their	O
use	O
is	O
deprecated	O
(	O
reverted	O
the	O
deprecation	O
since	O
2003	O
)	O
.	O
</s>
<s>
No	O
other	O
headers	O
in	O
the	O
C++	B-Language
Standard	B-Library
Library	I-Library
end	O
in	O
"	O
.h	O
"	O
.	O
</s>
<s>
Features	O
of	O
the	O
C++	B-Language
Standard	B-Library
Library	I-Library
are	O
declared	O
within	O
the	O
std	O
namespace	O
.	O
</s>
<s>
The	O
C++	B-Language
Standard	B-Library
Library	I-Library
is	O
based	O
upon	O
conventions	O
introduced	O
by	O
the	O
Standard	B-Application
Template	I-Application
Library	I-Application
(	O
STL	O
)	O
,	O
and	O
has	O
been	O
influenced	O
by	O
research	O
in	O
generic	B-Language
programming	I-Language
and	O
developers	O
of	O
the	O
STL	O
such	O
as	O
Alexander	O
Stepanov	O
and	O
Meng	O
Lee	O
.	O
</s>
<s>
Although	O
the	O
C++	B-Language
Standard	B-Library
Library	I-Library
and	O
the	O
STL	O
share	O
many	O
features	O
,	O
neither	O
is	O
a	O
strict	O
superset	O
of	O
the	O
other	O
.	O
</s>
<s>
A	O
noteworthy	O
feature	O
of	O
the	O
C++	B-Language
Standard	B-Library
Library	I-Library
is	O
that	O
it	O
not	O
only	O
specifies	O
the	O
syntax	O
and	O
semantics	O
of	O
generic	B-Language
algorithms	I-Language
,	O
but	O
also	O
places	O
requirements	O
on	O
their	O
performance	O
.	O
</s>
<s>
In	O
most	O
cases	O
this	O
requires	O
linear	O
time	O
O(n )	O
or	O
linearithmic	O
time	O
O(n log n )	O
,	O
but	O
in	O
some	O
cases	O
higher	O
bounds	O
are	O
allowed	O
,	O
such	O
as	O
quasilinear	O
time	O
O(n log2 n )	O
for	O
stable	O
sort	O
(	O
to	O
allow	O
in-place	B-Algorithm
merge	O
sort	O
)	O
.	O
</s>
<s>
Previously	O
,	O
sorting	O
was	O
only	O
required	O
to	O
take	O
O(n log n )	O
on	O
average	O
,	O
allowing	O
the	O
use	O
of	O
quicksort	B-Algorithm
,	O
which	O
is	O
fast	O
in	O
practice	O
but	O
has	O
poor	O
worst-case	O
performance	O
,	O
but	O
introsort	O
was	O
introduced	O
to	O
allow	O
both	O
fast	O
average	O
performance	O
and	O
optimal	O
worst-case	O
complexity	O
,	O
and	O
as	O
of	O
C++11	B-Language
,	O
sorting	O
is	O
guaranteed	O
to	O
be	O
at	O
worst	O
linearithmic	O
.	O
</s>
<s>
In	O
other	O
cases	O
requirements	O
remain	O
laxer	O
,	O
such	O
as	O
selection	B-Algorithm
,	O
which	O
is	O
only	O
required	O
to	O
be	O
linear	O
on	O
average	O
(	O
as	O
in	O
quickselect	B-Algorithm
)	O
,	O
not	O
requiring	O
worst-case	O
linear	O
as	O
in	O
introselect	B-Algorithm
.	O
</s>
<s>
The	O
C++	B-Language
Standard	B-Library
Library	I-Library
underwent	O
ISO	O
standardization	O
as	O
part	O
of	O
the	O
C++	B-Language
ISO	O
Standardization	O
effort	O
,	O
and	O
is	O
undergoing	O
further	O
work	O
regarding	O
standardization	O
of	O
expanded	O
functionality	O
.	O
</s>
<s>
The	O
Apache	B-Language
C++	I-Language
Standard	I-Language
Library	I-Language
is	O
another	O
open-source	O
implementation	O
.	O
</s>
<s>
However	O
,	O
after	O
more	O
than	O
five	O
years	O
without	O
a	O
release	O
,	O
the	O
board	O
of	O
the	O
Apache	O
Software	O
Foundation	O
decided	O
to	O
end	O
this	O
project	O
and	O
move	O
it	O
to	O
Apache	B-Application
Attic	I-Application
.	O
</s>
