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std::basic_ifstream::open(3)   C++ Standard Libary  std::basic_ifstream::open(3)

NAME
     std::basic_ifstream::open - std::basic_ifstream::open

Synopsis
	void open( const char* filename,

		   std::ios_base::openmode mode 		      (1)

		       = std::ios_base::in );
	void open( const std::filesystem::path::value_type* filename,

		   std::ios_base::openmode mode 		      (2) (since
     C++17)

		       = std::ios_base::in );
	void open( const std::string& filename,

		   std::ios_base::openmode mode 		      (3) (since
     C++11)

		       = std::ios_base::in );
	void open( const std::filesystem::path& filename,

		   std::ios_base::openmode mode 		      (4) (since
     C++17)

		       = std::ios_base::in );

	Opens and associates the file with name filename with the file stream.

	Calls clear() on success. Calls setstate(failbit) on failure.

	1,2) Effectively calls rdbuf()->open(filename, mode | ios_base::in) (see
	std::basic_filebuf::open for the details on the effects of that call).
	Overload  (2)  is  only provided if std::filesystem::path::value_type is
     not char.
	(since C++17)
	3,4) Effectively calls (1,2) as if by open(filename.c_str(), mode).

Parameters
	filename - the name of the file to be opened
		   specifies stream open mode. It is a BitmaskType, the  follow-
     ing constants
		   are defined:

		   Constant	     Explanation
		   app		     seek to the end of stream before each write
	mode	 - binary	     open in binary mode
		   in		     open for reading
		   out		     open for writing
		   trunc	      discard  the  contents  of the stream when
     opening
		   ate		     seek to the end of stream immediately after
     open
		   noreplace (C++23) open in exclusive mode

Return value
	(none)

Example
	 This section is incomplete
	 Reason: no example

	Defect reports

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

	  DR	 Applied to		Behavior as published		    Cor-
     rect behavior
	LWG 22	C++98	   it was unclear how error state changes  upon  a   the
     error state is
			   successful	open				     un-
     changed
	LWG 409 C++98	   the error state was unchanged upon a 	  it  is
     cleared^[1]
			   successful open

	 1. a The resolution of LWG issue #22 is overriden.

See also
	is_open checks if the stream has an associated file
		(public member function)
	close	closes the associated file
		(public member function)
	open	 opens	a file and configures it as the associated character se-
     quence
		(public member function of std::basic_filebuf<CharT,Traits>)

Category:
	  * Todo no example

http://cppreference.com 	   2024.06.10	    std::basic_ifstream::open(3)
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