istream& putback ( char c );

Put character back

Decrements the internal get pointer by one, and c becomes the character to be read at that position by the next input operation.

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

A subsequent call to member gcount will return zero.

Parameters

c

The character to be put back.

Return Value

Errors are signaled by modifying the internal state flags:

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

// istream putback
#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.putback (c);
    cin >> n;
    cout << "You have entered number " << n << endl;
  }
  else
  {
    cin.putback (c);
    cin >> str;
    cout << " You have entered word " << str << endl;
  }

  return 0;
}

Basic template member declaration

typedef charT char_type;
basic_istream& putback ( char_type c );

See also