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std::ostreambuf_iterator<CharT,Traits>:: ostreambuf_iterator

From cppreference.net
C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
std::ostreambuf_iterator
(1)
ostreambuf_iterator ( streambuf_type * buffer ) throw ( ) ;
(until C++11)
ostreambuf_iterator ( streambuf_type * buffer ) noexcept ;
(since C++11)
(2)
ostreambuf_iterator ( ostream_type & stream ) throw ( ) ;
(until C++11)
ostreambuf_iterator ( ostream_type & stream ) noexcept ;
(since C++11)
1) Constructs the iterator with the private streambuf_type* member set to buffer and the failed() flag set to false . The behavior is undefined if buffer is a null pointer.
2) Same as ostreambuf_iterator ( stream. rdbuf ( ) ) .

Parameters

stream - the output stream whose rdbuf() will be accessed by this iterator
buffer - the output stream buffer to be accessed by this iterator

Example

Run this code 
#include <fstream>
#include <iostream>
#include <iterator>
int main()
{
    const char* file = "test.txt";
    {
        std::basic_filebuf<char> f;
        f.open(file, std::ios::out);
        std::ostreambuf_iterator<char> out1(&f);
        *out1 = 'a'; // writes to file via iterator
    }
    // read back from the file
    char a;
    std::cout << ((std::ifstream{file} >> a), a) << std::endl;
    std::ostreambuf_iterator<wchar_t> out2{std::wcout};
    *out2 = L'b';
}

Output: 

a
b

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 112 C++98 the requirement "the argument cannot
be null" was applied to overload (2) 		applies to overload
(1) instead
P2325R3 C++20 default constructor was provided as C++20
iterators must be default_initializable 		removed along with
the requirement