std::basic_streambuf<CharT,Traits>::setp

#include <array>
#include <cstddef>
#include <iostream>
 
// Buffer for std::ostream implemented by std::array
template<std::size_t size, class CharT = char>
struct ArrayedStreamBuffer : std::basic_streambuf <CharT>
{
 using Base = std::basic_streambuf <CharT>;
 using char_type = typename Base::char_type;
 
 ArrayedStreamBuffer()
 {
 // put area pointers to work with "buffer"
 Base::setp(buffer.data(), buffer.data() + size);
 }
 
 void print_buffer()
 {
 for (char_type i : buffer)
 {
 if (i == 0)
 std::cout << "\\0";
 else
 std::cout << i;
 std::cout << ' ';
 }
 std::cout << '\n';
 }
 
private:
 std::array <char_type, size> buffer{}; // value-initialize "buffer"
};
 
int main()
{
 ArrayedStreamBuffer<10> streambuf;
 std::ostream stream(&streambuf);
 
 stream << "hello";
 stream << ",";
 
 streambuf.print_buffer();
}

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