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std::basic_...am::is_open(3)   C++ Standard Libary  std::basic_...am::is_open(3)

NAME
     std::basic_ifstream::is_open - std::basic_ifstream::is_open

Synopsis
	bool is_open() const;

	Checks if the file stream has an associated file.

	Effectively calls rdbuf()->is_open().

Parameters
	(none)

Return value
	true if the file stream has an associated file, false otherwise.

Example
     // Run this code

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

      // this file is called main.cpp

      bool file_exists(const std::string& str)
      {
	  std::ifstream fs(str);
	  return fs.is_open();
      }

      int main()
      {
	  std::boolalpha(std::cout);
	  std::cout << file_exists("main.cpp")	<< '\n'
		    << file_exists("strange_file") << '\n';
      }

Possible output:
      true
      false

	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  365  C++98       is_open  was not declared with const qualifier de-
     clared with const
									 quali-
     fier

See also
	open  opens a file and associates it with the stream
	      (public member function)
	close closes the associated file
	      (public member function)

http://cppreference.com 	   2024.06.10	    std::basic_...am::is_open(3)
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