std::basic_stringbuf::basic_stringbuf
From cppreference.com
< cpp | io | basic stringbuf
| basic_stringbuf() : basic_stringbuf(std::ios_base::in | std::ios_base::out) { } |
(1) | |
| (2) | ||
| explicit basic_stringbuf( std::ios_base::openmode which = std::ios_base::in | std::ios_base::out ); |
(until C++11) | |
| explicit basic_stringbuf( std::ios_base::openmode which ); |
(since C++11) | |
| explicit basic_stringbuf( const std::basic_string<CharT, traits, Allocator>& new_str, std::ios_base::openmode which = std::ios_base::in |
(3) | |
| basic_stringbuf( const basic_stringbuf& rhs ) = delete; |
(4) | (since C++11) |
| basic_stringbuf( basic_stringbuf&& rhs ); |
(5) | (since C++11) |
1) Default constructor. It is implementation-defined whether the sequence pointers (
eback(), gptr(), egptr(), pbase(), pptr(), epptr()) are initialized to null pointers. 2) Constructs a
std::basic_stringbuf object: initializes the base class by calling the default constructor of std::basic_streambuf, initializes the character sequence with an empty string, and sets the mode to which.3) Constructs a
std::basic_stringbuf object by performing the same initialization as 1), followed by initializing the associated character sequence as if by calling str(new_str).5) Move-constructs a
std::basic_stringbuf object by moving all state from another std::basic_stringbuf object rhs, including the associated string, the open mode, the locale, and all other state. After the move, the six pointers of std::basic_streambuf in *this are guaranteed to be different from the corresponding pointers in the moved-from rhs unless null.Parameters
| new_str | - | a basic_string used to initialize the buffer
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| rhs | - | another basic_stringbuf
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| which | - | specifies stream open mode. It is bitmask type, the following constants are defined:
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Notes
Typically called by the constructor of std::basic_stringstream.
The level of support for the open modes other than std::ios_base::in and std::ios_base::out varies among implementations. C++11 explicitly specifies the support for std::ios_base::ate in str() and in this constructor, but std::ios_base::app, std::ios_base::trunc, and std::ios_base::binary have different effects on different implementations.
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
Demonstrates calling the constructor of basic_stringbuf directly.
Run this code
#include <iostream> #include <sstream> int main() { // default constructor (mode = in|out) std::stringbuf buf1; buf1.sputc('1'); std::cout << &buf1 << '\n'; // string constructor in at-end mode (C++11) std::stringbuf buf2("test", std::ios_base::in | std::ios_base::out | std::ios_base::ate); buf2.sputc('1'); std::cout << &buf2 << '\n'; // append mode test (results differ among compilers) std::stringbuf buf3("test", std::ios_base::in | std::ios_base::out | std::ios_base::app); buf3.sputc('1'); buf3.pubseekpos(1); buf3.sputc('2'); std::cout << &buf3 << '\n'; }
Output:
1 test1 est12 (Sun Studio) 2st1 (GCC)
See also
| constructs the string stream (public member function of std::basic_stringstream) |