This document discusses file input and output streams in C++. It explains that files allow permanent storage of data on secondary storage devices. There are three main stream classes for files - ofstream for output, ifstream for input, and fstream for both input and output. Streams are used to read from and write to files similar to how cin and cout are used for keyboard and screen input/output. The data hierarchy is also covered, ranging from bits to files organized in databases.

1. Sanjivani Rural Education Society’s
Sanjivani College of Engineering, Kopargaon-423 603
(An Autonomous Institute, Affiliated to Savitribai Phule Pune University, Pune)
NAAC ‘A’ Grade Accredited, ISO 9001:2015 Certified
Department of Computer Engineering
(NBA Accredited)
Prof. I. B. Tirse
Assistant Professor
E-mail :tirseishwaricomp@sanjivani.org.in
Contact No: 7507113718
Subject- Object Oriented Programming (CO212)
Unit 5 – Files and Streams
Topic – 5.1 Data Hierarchy, Stream and Files, Stream
Classes

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• All programs we looked earlier:
Introduction to files
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input data from the keyboard.
output data to the screen.
• Output would be lost as soon as we exit from the program.
• How do we store data permanently?
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We can use secondary storage device.
Data is packaged up on the storage device as
data structures called files.

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Streams Usage
• We have used streams already
 c i n
Input from stream object connected to keyboard
cout
Output to stream object connected to screen
• C a n define other streams
 To or from files
Used similarly as cin, cout

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File input and output streams

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Streams
 File Input Stream – reads data from disk file to the program.
 The I/O system of C++ contains following classes :
 File output Stream – writes data to the disk file from the program.
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ofstream – provides output operations on files
fstream – supports for simultaneous input and
output operations on files
ifstream – provides input operations on files

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Stream Classes

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The Data Hierarchy
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 From smallest to largest
 Bit (binary digit)
 1 or 0
 Everything in computer ultimately represented as
bits
 Character set
 Digits, letters, symbols used to represent data
 Every character represented by 1's and 0's
 Byte: 8 bits
 Can store a character (char)

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The Data Hierarchy (contd.)
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 From smallest to largest (continued)
Field: group of characters with some meaning
e.g., Your name
Record: group of related fields
 struct or class in C++
File: group of related records
Payroll for entire company
Database: group of related files
Payroll, accounts-receivable.

9. Thank You..
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