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
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::istream

constructor member
explicit  istream (streambuf * sb);

Construct object

Constructs an object, assigning initial values to the base class by calling the inherited member ios::init with sb as parameter.

Parameters

sb
pointer to a streambuf object, which is set as the associated stream buffer for the object.

Return Value

None (constructor).

Example

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// istream constructor
#include <iostream>
#include <fstream>
using namespace std;
int main () {
  filebuf fb;
  fb.open ("test.txt",ios::in);
  istream is(&fb);
  cout << char(is.get());
  fb.close();
  return 0;
}


This code uses a filebuf object (derived from streambuf) to open the file test.txt. The buffer is passed as parameter to the constructor of the istream object is, associating it to the stream. Then the first character is read and sent to the standard output stream cout.

Objects of class istream are seldom constructed directly. Generally some derived class is used (like the standard ones ifstream and istringstream).

Basic template member declaration

( basic_istream<charT,traits> )
  
explicit basic_istream ( basic_streambuf<charT,traits>* sb );


See also

ios_base::Init Initialize standard stream objects (public member class)