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std::ios_base::openmode(3)     C++ Standard Libary    std::ios_base::openmode(3)

NAME
     std::ios_base::openmode - std::ios_base::openmode

Synopsis
	typedef /* implementation defined */ openmode;
	static constexpr openmode app	    = /* implementation defined */;

	static constexpr openmode binary    = /* implementation defined */;
	static constexpr openmode in	    = /* implementation defined */;
	static constexpr openmode out	    = /* implementation defined */;
	static constexpr openmode trunc     = /* implementation defined */;

	static constexpr openmode ate	    = /* implementation defined */;
	static	constexpr  openmode  noreplace	=  /* implementation defined */;
     (since C++23)

	Specifies available file open flags. It is a BitmaskType, the  following
     constants
	are defined:

	Constant	  Explanation
	app		  seek to the end of stream before each write
	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

Example
     // Run this code

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

      int main()
      {
	  const char* fname = "unique_name.txt";

	  // write to a temporary stream object
	  std::fstream(fname, std::ios::out | std::ios::trunc) << "Hi";

	  std::string s;
	  std::fstream(fname, std::ios::in) >> s;
	  std::cout << s << '\n';
      }

Output:
      Hi

See also
	open	      opens a file and configures it as the associated character
     sequence
		      (public	  member     function	  of	std::basic_file-
     buf<CharT,Traits>)
		      constructs a basic_stringbuf object
	constructor   (public member function of
		      std::basic_stringbuf<CharT,Traits,Allocator>)

http://cppreference.com 	   2024.06.10	      std::ios_base::openmode(3)

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