Reference
C Library
IOstream Library
Strings library
STL Containers
STL Algorithms
Miscellaneous
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
streambuf
streambuf::streambuf
streambuf::~streambuf
public members:
streambuf::getloc
streambuf::in_avail
streambuf::pubimbue
streambuf::pubseekoff
streambuf::pubseekpos
streambuf::pubsetbuf
streambuf::pubsync
streambuf::sbumpc
streambuf::sgetc
streambuf::sgetn
streambuf::snextc
streambuf::sputbackc
streambuf::sputc
streambuf::sputn
streambuf::sungetc
protected members:
streambuf::eback
streambuf::egptr
streambuf::epptr
streambuf::gbump
streambuf::gptr
streambuf::pbase
streambuf::pbump
streambuf::pptr
streambuf::setg
streambuf::setp
virtual prot. members:
streambuf::imbue
streambuf::overflow
streambuf::pbackfail
streambuf::seekoff
streambuf::seekpos
streambuf::setbuf
streambuf::showmanyc
streambuf::sync
streambuf::uflow
streambuf::underflow
streambuf::xsgetn
streambuf::xsputn


streambuf::sungetc

public member function
int sungetc ( );

Decrease get pointer

Moves the get pointer one character backwards, making the last character gotten by an input operation available once again for the next input operation.

During its operation, the function will call the protected virtual member function pbackfail if the get pointer gptr points to the same position as the beginning pointer eback.

Parameters

none

Return Value

The value of the character in the new get pointer position.
If the get pointer is at the beginning of the input sequence the function returns EOF (or traits::eof() for other traits).

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
 
// sungetc
#include <iostream>
using namespace std;
int main () {
  char ch;
  long n;
  streambuf * pbuf;
  pbuf = cin.rdbuf();
  cout << "Please enter some letters and after a number: ";
  do {
    ch=pbuf->sbumpc();
    if ( (ch>='0') && (ch <='9') )
    {
      pbuf->sungetc ();
      cin >> n;
      cout << "You entered number " << n << endl;
      break;
    }
  } while (ch != EOF);
  return 0;
}


This example gets characters form standard input one by one. When the first numeric digit is found, sungetc is called to restore the position in the stream to that digit in order to be extracted as part of a number using the extraction operator >>.

Basic template member declaration

( basic_streambuf<charT,traits> )
1
2
 
typedef traits::int_type int_type;
int_type sungetc ( );


See also

streambuf::sputbackc Put character back (public member function)
streambuf::sgetc Get current character (public member function)
streambuf::snextc Increase get pointer and return next character (public member function)
streambuf::sbumpc Get current character and increase get pointer (public member function)
streambuf::sputc Store character at current put position and increase put pointer (public member function)