istream::unget


public member function
istream& unget ( );

Decrement get pointer

Decrements the internal get pointer by one, making the last character extracted from the input sequence available again as the next character to be read from the stream.

The function effectively calls the sungetc member function of the streambuf object associated to the stream.

A subsequent call to member gcount will return zero.

Parameters

none

Return Value

The function returns *this.

Errors are signaled by modifying the internal state flags:

flagerror
eofbit-
failbitThe stream was at the end of the source of characters before the function was called.
badbitAn error other than the above happened.


Additionaly, in any of these cases, if the appropriate flag has been set with member function ios::exceptions, an exception of type ios_base::failure is thrown.

Example

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// read entire file into memory
#include <iostream>
using namespace std;

int main () {
  char c;
  int n;
  char str[256];

  cout << "Enter a number or a word: ";
  c = cin.get();

  if ( (c >= '0') && (c <= '9') )
  {
    cin.unget();
    cin >> n;
    cout << "You have entered number " << n << endl;
  }
  else
  {
    cin.unget();
    cin >> str;
    cout << " You have entered word " << str << endl;
  }

  return 0;
}


Basic template member declaration

(basic_istream<charT,traits>)
  
basic_istream& unget ( );


See also

istream::get Get unformatted data from stream (public member function)
istream::putback Put character back (public member function)