std::basic_streambuf<CharT,Traits>::pbump (3) - Linux Manuals

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


std::basic_streambuf<CharT,Traits>::pbump - std::basic_streambuf<CharT,Traits>::pbump


void pbump( int count );

Repositions the put pointer (pptr()) by count characters, where count may be positive or negative. No checks are done for moving the pointer outside the put area [pbase(), epptr()).
If the pointer is advanced and then overflow() is called to flush the put area to the associated character sequence, the effect is that extra count characters with undefined values are output.


count - number to add to the put pointer

Return value



Because this function takes an int, it cannot manipulate buffers larger than std::numeric_limits<int>::max() characters (LWG_255)


// Run this code

  #include <iostream>
  #include <string>
  #include <fstream>

  struct showput_streambuf : std::filebuf
      using std::filebuf::pbump; // expose protected
      std::string showput() const {
          return std::string(pbase(), pptr());

  int main()
      showput_streambuf mybuf;"test.txt", std::ios_base::out);
      std::ostream str(&mybuf);
      str << "This is a test" << std::flush << "1234";
      std::cout << "The put area contains: " << mybuf.showput() << '\n';
      std::cout << "after pbump(10), it contains " << mybuf.showput() << '\n';


  The put area contains: 1234
  after pbump(10), it contains 1234 is a test

See also

      advances the next pointer in the input sequence
gbump (protected member function)