std::strstreambuf:: strstreambuf
From cppreference.com
<
cpp
|
io
|
strstreambuf
| (1) | ||
|
explicit
strstreambuf
(
std::
streamsize
alsize
=
0
)
;
|
(deprecated in C++98)
(until C++11) |
|
|
strstreambuf
(
)
:
strstreambuf
(
0
)
{
}
explicit strstreambuf ( std:: streamsize alsize ) ; |
(since C++11) (removed in C++26) | |
|
strstreambuf
(
void
*
(
*
palloc
)
(
std::
size_t
)
,
void
(
*
pfree
)
(
void
*
)
)
;
|
(2) |
(deprecated in C++98)
(removed in C++26) |
|
strstreambuf
(
char
*
gnext,
std::
streamsize
n,
char
*
pbeg
=
0
)
;
|
(3) |
(deprecated in C++98)
(removed in C++26) |
|
strstreambuf
(
signed
char
*
gnext,
std::
streamsize
n,
signed
char
*
pbeg
=
0
)
;
|
(4) |
(deprecated in C++98)
(removed in C++26) |
|
strstreambuf
(
unsigned
char
*
gnext,
std::
streamsize
n,
unsigned
char
*
pbeg
=
0
)
;
|
(5) |
(deprecated in C++98)
(removed in C++26) |
|
strstreambuf
(
const
char
*
gnext,
std::
streamsize
n
)
;
|
(6) |
(deprecated in C++98)
(removed in C++26) |
|
strstreambuf
(
const
signed
char
*
gnext,
std::
streamsize
n
)
;
|
(7) |
(deprecated in C++98)
(removed in C++26) |
|
strstreambuf
(
const
unsigned
char
*
gnext,
std::
streamsize
n
)
;
|
(8) |
(deprecated in C++98)
(removed in C++26) |
1)
Constructs a
std::strstreambuf
object: initializes the base class by calling the default constructor of
std::streambuf
, initializes the buffer state to "dynamic" (the buffer will be allocated as needed), initializes allocated size to the provided
alsize
, initializes the allocation and the deallocation functions to null (will use
new
[
]
and
delete
[
]
).
2)
Constructs a
std::strstreambuf
object: initializes the base class by calling the default constructor of
std::streambuf
, initializes the buffer state to "dynamic" (the buffer will be allocated as needed), initializes allocated size to unspecified value, initializes the allocation function to
palloc
and the deallocation function to
pfree
.
3-5)
Constructs a
std::strstreambuf
object in following steps:
a)
Initializes the base class by calling the default constructor of
std::streambuf
.
b)
Initializes the buffer state to "constant" (the buffer is a user-provided fixed-size buffer).
c)
Determines the number of elements in the user-provided array as follows: if
n
is greater than zero,
n
is used. If
n
is zero,
std::
strlen
(
gnext
)
is executed to determine the buffer size. If
n
is negative,
INT_MAX
is used.
d)
Configures the
std::basic_streambuf
pointers as follows: If
pbeg
is a null pointer, calls
setg
(
gnext, gnext, gnext
+
N
)
. If
pbeg
is not a null pointer, executes
setg
(
gnext, gnext, pbeg
)
and
setp
(
pbeg, pbeg
+
N
)
, where N is the number of elements in the array as determined earlier.
6-8)
Same as
strstreambuf
(
(
char
*
)
gnext, n
)
, except the "constant" bit is set in the buffer state bitmask (output to this buffer is not allowed).
Parameters
| alsize | - | the initial size of the dynamically allocated buffer |
| palloc | - | pointer to user-provided allocation function |
| pfree | - | pointer to user-provided deallocation function |
| gnext | - | pointer to the start of the get area in the user-provided array |
| pbeg | - | pointer to the start of the put area in the user-provided array |
| n | - | the number of bytes in the get area (if pbeg is null) or in the put area (if pbeg is not null) of the user-provided array |
Notes
These constructors are typically called by the constructors of std:: strstream .
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| P0935R0 | C++11 | default constructor was explicit | made implicit |
Example
Run this code
#include <iostream> #include <strstream> int main() { std::strstreambuf dyn; // dynamic std::strstream dyn_s; // equivalent stream dyn_s << 1.23 << std::ends; std::cout << dyn_s.str() << '\n'; dyn_s.freeze(false); char buf[10]; std::strstreambuf user(buf, 10, buf); // user-provided output buffer std::ostrstream user_s(buf, 10); // equivalent stream user_s << 1.23 << std::ends; std::cout << buf << '\n'; std::strstreambuf lit("1 2 3", 5); // constant std::istrstream lit_s("1 2 3"); // equivalent stream int i, j, k; lit_s >> i >> j >> k; std::cout << i << ' ' << j << ' ' << k << '\n'; }
Output:
1.23 1.23 1 2 3
See also
constructs a
strstream
object, optionally allocating the buffer
(public member function of
std::strstream
)
|