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

NAME
     std::basic_istream::unget - std::basic_istream::unget

Synopsis
	basic_istream& unget();

	Makes the most recently extracted character available again.

	First, clears eofbit. Then,
	(since	C++11)	unget  behaves	as  UnformattedInputFunction. After con-
     structing and
	checking the sentry object, if any ios_base::iostate flags are set,  the
     function
	sets failbit and returns. Otherwise, calls rdbuf()->sungetc().

	If rdbuf()->sungetc() returns Traits::eof(), calls setstate(badbit).

	In any case, sets the gcount() counter to zero.

Parameters
	(none)

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
     // Run this code

      #include <iostream>
      #include <sstream>

      int main()
      {
	  std::istringstream s1("Hello, world.");
	  char c1 = s1.get();
	  if (s1.unget())
	  {
	      char c2 = s1.get();
	      std::cout << "Got: '" << c1 << "'. Got again: '" << c2 << "'.\n";
	  }
      }

Output:
      Got: 'H'. Got again: 'H'.

See also
	sungetc moves the next pointer in the input sequence back by one
		(public member function of std::basic_streambuf<CharT,Traits>)
	get	extracts characters
		(public member function)
	peek	reads the next character without extracting it
		(public member function)
	putback puts a character into input stream
		(public member function)

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