Reference
C Library
IOstream Library
Strings library
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IOstream Library
manipulators
classes:
filebuf
fstream
ifstream
ios
iostream
ios_base
istream
istringstream
ofstream
ostream
ostringstream
streambuf
stringbuf
stringstream
objects:
cerr
cin
clog
cout
types:
fpos
streamoff
streampos
streamsize

istream
istream::istream
istream::~istream
member classes:
istream::sentry
member functions:
istream::gcount
istream::get
istream::getline
istream::ignore
istream::operator>>
istream::peek
istream::putback
istream::read
istream::readsome
istream::seekg
istream::sync
istream::tellg
istream::unget

istream::putback

public member function

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

The function returns *this
Errors are signaled by modifying the internal state flags:

flag	error
`eofbit`	-
`failbit`	The stream was at the end of the source of characters before the function was called.
`badbit`	An error other than the above happened.

Additionally, 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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// 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

( basic_istream<charT,traits> )

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

istream::putback

Parameters

Return Value

Example

Basic template member declaration

See also