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std::basic_istream::basic_istream(3) | C++ Standard Libary | std::basic_istream::basic_istream(3) |
NAME¶
std::basic_istream::basic_istream - std::basic_istream::basic_istream
Synopsis¶
explicit basic_istream( std::basic_streambuf<CharT,
Traits>* sb ); (1)
protected: (2) (since C++11)
basic_istream( const basic_istream& rhs ) = delete;
protected: (3) (since C++11)
basic_istream( basic_istream&& rhs );
1) Constructs the basic_istream object, assigning initial values to the base
class
by calling basic_ios::init(sb). The value of gcount() is initialized to
zero.
2) The copy constructor is protected, and is deleted. Input streams are not
copyable.
3) The move constructor copies the value of gcount() from rhs, sets the
gcount()
value of rhs to zero, and uses basic_ios<CharT, Traits>::move(rhs) to
move all
basic_ios members, except for the rdbuf(), from rhs into *this. This move
constructor is protected: it is called by the move constructors of movable
input
stream classes std::basic_ifstream and std::basic_istringstream, which know
how to
correctly move the associated stream buffer.
Parameters¶
sb - streambuffer to use as underlying device
Example¶
// Run this code
#include <iostream>
#include <sstream>
int main()
{
std::istringstream s1("hello");
std::istream s2(s1.rdbuf()); // OK: s2 shares the buffer with s1
// std::istream s3(std::istringstream("test")); // ERROR: move
constructor is protected
// std::istream s4(s2); // ERROR: copy constructor is deleted
std::istringstream s5(std::istringstream("world")); // OK: move
ctor called
// by derived class
std::cout << s2.rdbuf() << ' ' << s5.rdbuf() << '\n';
}
Output:¶
hello world
2024.06.10 | http://cppreference.com |