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std::strstr...uf::overflow(3)  C++ Standard Libary std::strstr...uf::overflow(3)

NAME
     std::strstreambuf::overflow - std::strstreambuf::overflow

Synopsis
	protected:					(deprecated in C++98)
	virtual int_type overflow( int_type c = EOF );	(removed in C++26)

	Appends  the  character c to the put area of the buffer, reallocating if
     possible.

	1) If c == EOF, does nothing.
	2) Otherwise, if the put area has a write position available  (pptr()  <
     epptr()),
	stores the character as if by *pptr()++ = c.
	3)  Otherwise,	if  the  stream buffer mode is not dynamic or the stream
     buffer is
	currently frozen, the function fails and returns EOF.
	4) Otherwise, the function reallocates (or initially  allocates)  a  dy-
     namic array
	large  enough to hold the contents of the current dynamic array (if any)
     plus at
	least one additional write position. If  a  pointer  to  the  allocating
     function palloc
	was  used  in the constructor, that function is called with (*palloc)(n)
     where n is
	the number of bytes to allocate, otherwise new char[n]	is  used.  If  a
     pointer to the
	deallocating  function	pfree was used in the constructor, that function
     is called
	with (*pfree)(p) to deallocate the previous array, if needed,  otherwise
     delete[] p
	is used. If allocation fails, the function fails and returns EOF.

Parameters
	c - the character to store in the put area

Return value
	If  c == EOF, returns some value other than EOF. Otherwise, returns (un-
     signed
	char)(c) on success, EOF on failure.

Example
     // Run this code

      #include <iostream>
      #include <strstream>

      struct mybuf : std::strstreambuf
      {
	  int_type overflow(int_type c)
	  {
	      std::cout << "Before overflow(): size of the  put  area  is  "  <<
     epptr()-pbase()
			<<  "  with  "	<<  epptr()-pptr()  << " write positions
     available\n";
	      int_type rc = std::strstreambuf::overflow(c);
	      std::cout << "After overflow(): size of  the  put  area  is  "  <<
     epptr()-pbase()
			<<  "  with  "	<<  epptr()-pptr()  << " write positions
     available\n";
	      return rc;
	  }
      };

      int main()
      {
	  mybuf sbuf; // read-write dynamic strstreambuf
	  std::iostream stream(&sbuf);

	  stream << "Sufficiently long string to overflow  the	initial  alloca-
     tion, at least "
		 << " on some systems.";
      }

Possible output:
      Before  overflow():  size  of  the  put  area is 16 with 0 write positions
     available
      After overflow(): size of the put area  is  32  with  15	write  positions
     available
      Before  overflow():  size  of  the  put  area is 32 with 0 write positions
     available
      After overflow(): size of the put area  is  64  with  31	write  positions
     available
      Before  overflow():  size  of  the  put  area is 64 with 0 write positions
     available
      After overflow(): size of the put area is  128  with  63	write  positions
     available

See also
	overflow   writes  characters to the associated output sequence from the
     put area
	[virtual]  (virtual  protected	member	function  of  std::basic_stream-
     buf<CharT,Traits>)

	overflow  appends a character to the output sequence
	[virtual] (virtual protected member function of
		  std::basic_stringbuf<CharT,Traits,Allocator>)
	overflow  writes characters to the associated file from the put area
	[virtual]   (virtual   protected  member  function  of	std::basic_file-
     buf<CharT,Traits>)

	sputc	  writes one character to the put area	and  advances  the  next
     pointer
		  (public member function of std::basic_streambuf<CharT,Traits>)
	put	  inserts a character
		  (public member function of std::basic_ostream<CharT,Traits>)

http://cppreference.com 	   2024.06.10	   std::strstr...uf::overflow(3)
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