This document discusses input and output streams in C++. It covers the stream classes ifstream, ofstream, and fstream for reading from and writing to files. It explains that files must be opened before reading from or writing to them using the open() function. Data can then be written to files using the insertion operator << and read from files using the extraction operator >>, similar to standard input/output. The document provides examples of opening, reading, and writing files in C++.

1. Streams and Files:
Chapter 12:
Ms. Munazza Mah Jabeen
Assistant Professor of Computer Science

2. Stream Classes:
• A stream is a general name given to a flow of data.
iostream standard library provide cin and cout methods
for reading from standard input and writing to standard
output respectively.
• To read and write from a file we need another standard
C++ library called fstream, which defines three new data
types:
• ofstream
• ifstream
• fstream
• To perform file processing in C++, header files <iostream>
and <fstream> must be included in your C++ source file
• The extraction operator >> is a
• member of the istream class, and the insertion operator
<< is a member of the ostream class.

3. Opening / Closing a File:
• A file must be opened before you can read from it or write to it. Either
the ofstream or fstream object may be used to open a file for writing
and ifstream object is used to open a file for reading purpose only.
standard syntax for open() function:
void open(const char *filename, ios::openmode mode)
To open a file in write mode or truncate it if it exists
ofstream outfile;
outfile.open("file.dat", ios::out | ios::trunc );
fstream afile;
afile.open("file.dat", ios::out | ios::in )
• To close a File:
standard syntax for close() function
void close();

4. Reading / Writing a File:
• In order to write to a file we use the
stream insertion operator (<<) just
sending output to the screen. The
only difference is that you use an
ofstream or fstream object instead
of the cout object.
• To read information from a file use
the stream extraction operator (>>)
just like input information from the
keyboard. The only difference is that
you use an ifstream or fstream
object instead of the cin object.

5. Strings with Embedded Blanks:

6. Object I/O:

7. I/O with Multiple Objects:

8. Error Handling in File I/O: