Console input output operation in c++.

1. CONSOLEI/O 1
Managing Console
I/O Operations
Prepared By : Darshan Radadiya(Computer
Engineering)

2. CONSOLEI/O 2
Input and Output Stream
Que:
1. Explain input and output streams in C++.
2. Explain Input stream and Output stream in brief.
3. Describe briefly the features of I/O system supported by C++.
Ans:
 I/O System in C++ is designed to work with variety of devices including terminals, disks
and tape drives.
 I/O system supplies an interface to the programmer. This interface is known as stream.
 A stream is a sequence of bytes.
 Stream acts either as source from which the input data can be obtained or as a destination
to which the output data can be sent.
 The source stream that provides data to the program is called the input stream.
 The destination stream that receives output from the program is called the output stream.
 A program extracts the bytes from an input stream and inserts bytes into an output stream.
 Data in the input stream can come from the keyboard or any file. The data in the output
stream can go to the screen or any file.
 Stream acts as an interface between the program and the Input/Output device.
 C++ contains several predefined streams like: cin and cout
 Cin represents the input stream connected with keyboard.
 Cout represents the output stream connected to the screen.

3. CONSOLEI/O 3
C++ Stream Classes
Que:
1. Explain C++ Stream class hierarchy.
2. List out C++ steam classes.
Ans:
 The C++ I/O system contains a hierarchy of classes. These classes are called stream
classes.
 Stream classes are used to define various streams to deal with both the console and disk
file.
 Fig. shows the hierarchy of the stream classes used for input and output operations with
the console unit.
ios class (Input/Output Stream)
- ios is the base class for istream (input stream) and ostream(output stream).
- ios class declares constants and functions that are required for handling formatted input and
output operations.
istream (Input Stream) class
- It is inherited from class ios. It declares input function such as get(), getline() and read().
ostream (Output Stream) class
- It is also inherited from class ios. It declares output functions such as put() and write().

4. CONSOLEI/O 4
iostream (Input/Output Stream)
- It is the Input/Output stream.
- It is inherited from istream and ostream and thus containing all the input/output operations.
- Two objects of this class cin and cout uses the overloaded operators ‘>>’ and ‘<<’.
Streambuf (Stream buffer)
- It provides interface to physical devices through buffers; it acts as a base for filebuf class used
in files.
Class Name Contents
ios (General
I/O stream
class)
 Contains basic facilities that are used by all other input and output classes.
 Also contains a pointer to a buffer object.
 Declares constants and functions that are necessary for handling formatted
input and output functions.
istream (Input
stream)
 Inherits the properties of ios.
 Declares input functions such as get(), getline() andread()
 Contains overloaded extraction operator >>
ostream
(output stream)
 Inherits the properties of ios.
 Declares output functions such as put() and write()
 Contains overloaded insertion operator <<
iostream (I/O
stream)
 Inherits the properties of ios,istream and ostream through multiple
inheritance and thus contains all the input and output functions.
streambuf  Provides an interface to physical devices through buffers.
 Acts as a base for filebuf class used ios files.

5. CONSOLEI/O 5
Unformatted I/O Operations
Que:
1. Explain the functions get() , put() , getline() with example.
Ans:
Overloaded Operators >> and <<
 We have used the objects cin and cout for the input and output of data of various types.
 Input and output is possible by overloading the operators >> and <<.
 The ‘>>’ operator is overloaded in the istream class.
 The ‘<<’ operator is overloaded in the ostream class.
 The following is general format for reading data from the keyboard:
cin>>a>>b>>c;
 The general form for displaying data on the screen is:
cout>>a>>b>>c;
 Example:
#include <iostream.h>
int main()
{
int a;
cout<<"Enter the number";
cin>>a;
cout<<"The value of a="<<a;
return(0);
}
put() and get() functions
 get() and put() are used to handle the single character input/output operations.
get() function:
 There are two types of get() functions:
1. get(char *)
2. get(void)
1. get(char *)
 It fetches a character including the blank space, tab and newline character.
 It assigns the input character to its argument.
 Example:
char ch;
cin.get(ch);
2. get(void)
 It fetches a character including the blank space, tab and newline character.
 It returns the input character.

6. CONSOLEI/O 6
 Example:
char ch;
ch=cin.get();
put() function:
 Put() function is a member of ostream class.
 It can be used to putput a line of text character by character.
 Example:
char ch=’A’;
cout.put(ch);
Example of get(char*), and put():
#include <iostream.h>
int main()
{
int a=65; char ch;
cin.get(ch);
cout.put(ch);
ch=cin.get();
cout.put(ch);
cout.put(a);
return 0;
}
getline() and write() functions
 It is used to reads a whole line of text that ends with a newline character.
 Syntax:
cin.getline (line, size);
 First argument represents the name of string and second argument indicates the number of
character to be read.
 Example:
char name[20];
int size=10;
cin.getline(name,size);
write()
 It is used to display whole line of text on output device.
 Syntax:
cout.write (line, size);
 First argument represents the name of string and second argument indicates the number of
character to be display.
 Example:

7. CONSOLEI/O 7
char name[20];
int size=10;
cout.write (name, size);
Example of getline() and write():
#include <iostream.h>
int main()
{
int size=5;
char name[50];
cin.getline(name,size);
cout.write(name,size);
return 0;
}