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std::basic_istream::ignore(3)  C++ Standard Libary std::basic_istream::ignore(3)

NAME
     std::basic_istream::ignore - std::basic_istream::ignore

Synopsis
	basic_istream&	ignore(  std::streamsize  count  =  1,	int_type delim =
     Traits::eof()
	);

	Extracts and discards characters from the input stream until and includ-
     ing delim.

	ignore behaves as an UnformattedInputFunction.	After  constructing  and
     checking the
	sentry	object, it extracts characters from the stream and discards them
     until any of
	the following conditions occurs:

	  * count characters were extracted. This test is disabled in  the  spe-
     cial case when
	    count equals std::numeric_limits<std::streamsize>::max().
	  *  end  of file conditions occurs in the input sequence, in which case
     the function
	    calls setstate(eofbit).
	  * the next available character c in the input sequence  is  delim,  as
     determined by
	    Traits::eq_int_type(Traits::to_int_type(c),  delim).  The  delimiter
     character is
	    extracted  and  discarded.	This  test  is	disabled  if  delim   is
     Traits::eof().

Parameters
	count - number of characters to extract
	delim  -  delimiting character to stop the extraction at. It is also ex-
     tracted

Return value
	*this

Exceptions
	failure if an error occurred (the error state flag is not  goodbit)  and
     exceptions()
	is set to throw for that state.

	If an internal operation throws an exception, it is caught and badbit is
     set. If
	exceptions() is set for badbit, the exception is rethrown.

Example
	The following example uses ignore to skip over non-numeric input:

     // Run this code

      #include <iostream>
      #include <limits>
      #include <sstream>

      constexpr auto max_size = std::numeric_limits<std::streamsize>::max();

      int main()
      {
	  std::istringstream input("1\n"
				   "some non-numeric input\n"
				   "2\n");
	  for (;;)
	  {
	      int n;
	      input >> n;

	      if (input.eof() || input.bad())
		  break;
	      else if (input.fail())
	      {
		  input.clear(); // unset failbit
		  input.ignore(max_size, '\n'); // skip bad input
	      }
	      else
		  std::cout << n << '\n';
	  }
      }

Output:
      1
      2

	Defect reports

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

	  DR	Applied to	  Behavior  as	published		 Correct
     behavior
	LWG  172  C++98       the  type of count was misspecified   corrected to
     std::streamsize
			   as int

See also
	get	extracts characters
		(public member function)
	getline extracts characters until the given character is found
		(public member function)

http://cppreference.com 	   2024.06.10	   std::basic_istream::ignore(3)
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