Details in managing console of I/o operations & working with files

1. M.SUJITHA,
M.SC Student,
N.S College, Theni.

2. C++ STREAM CLASSES

3.  The features that supports to format the console
I/O operations are:
◦ Ios class functions and flags
◦ Manipulators
◦ User-defined output functions
IOS CLASS FUNCTIONS AND FLAGS:
It consists of large number of member
functions that is used to format the output in
number of ways.

4.  MANIPULATORS:
These are the special functions that are
included in the I/O statements to format the parameters
of a stream.
 DEFINING FIELD WIDTH:
◦ It is used to define the width of the field.
◦ Can be defined using width();
SETTING PRECISION:
 It is used to specify the to be displayed after the decimal
point.
FILLING AND PADDING:
 It is used to print the values using the larger field widths.
 It can be declared by,
cout.fill();

5. It is used for defining the input and
output in various forms.
Overloaded Operators >> and <<:
• It is used to give the I/O
• The >> is overloaded in istream class
• The << is overloaded in ostream class
Ex:
cin>>item1>>item2;

6. put() and get() Functions:
◦ It is used for the input and output .
◦ Put(c) is used to give the input
◦ Get(c) is used to get the output
Getline() and write() Functions:
• The getline() function reads a whole line of the
text and ends with a newline character.
• This function can be invoked by,
cin.getline (line,size);
• The writeline() function reads a whole line of the
text and displays an entire line.
• This function can be invoked by,
cout.write (line,size);

7.  The header file iomanip provides a set of functions called
manipulators which can be used to manipulate the output
formats.
 They provide the same features as that of the ios member
function and flag.
 Two or more manipulators can be,
 Cout<<manip1<<manip1<<manip<<item;
 Cout<<manip1<<item1<<manip2<<item2;

8.  The large amount of Data can be handled using
some devices such as floppy disk or hard disk to
store those datas.
 These datas are stored in these devices called
FILES.
 The Programs can be designed to perform the
read and write operations on those files.
 Kinds of Data Communication:
◦ Data Transfer between the console unit and the
program.
◦ Data Transfer between the program and a Diskfile.

9.  The I/O system contains a set of classes that define the
file handling methods.
 These includes ifstream, ofstream and fstream.
 These classes are derived from fstreambase and from the
corresponding iostream class.
 These classes are designed to manage the Disk files,
which are declared in fstream and we should include any
program in these files.

10.  A file stream can be declared using the classes ifstream, ofstream
and fstream that are contained in the Header file fstream.
A file can be Opened into two ways:
Using the Constructor function of the class
Using the Member function open() of the class
OPENING FILES USING Open():
 The function open() can be used to open multiple files that
use the same stream object.
file-stream-class stream-object;
stream-object.open (“file name”);

11. This condition is necessary for preventing
and read data from the file.
MORE ABOUT OPEN( ): FILE MODES
The function open( ) is used to open a new
and an existing file.
stream-object. open(“file
name”,mode);

12. Each file has two associated pointers
known as File pointers.
DEFAULT ACTIONS:
When we open a file in read-only-mode
,these input pointer is automatically set
at the beginning.
FUNCTIONS FOR MANIPULATION OF FILE POINTERS:
 seekg()-Moves a pointer to specified location
 seekp()-Moves put pointer to a specified location
 tellg()-Gives the current position of the get pointer
 tellp()-Gives the current position of the put pointer

13. It supports a number of member function for performing the
input/output operations on files.
Put() and get() Functions:
◦ It is used to handle single character at a time.
◦ The function put() writes a single character to the associated
stream.
◦ The function get() reads a single character to the associated
stream.
Write() and read() Functions:
◦ It is used to read and write the blocks in the binary data.

14.  It is used to maintain the routine task in the
data file.
 The updation can be done in:
◦ Displaying the contents of a file
◦ Modifying an existing item
◦ Adding a new file
◦ Deleting an existing file

15.  The reading and writing files may not be true always.
◦ A file which we are attempting to open for reading does not
exist.
◦ The file name used for a new file may already exist.
◦ We may use an invalid file name.
◦ There may not be any space in the disk for storing more data.
◦ We may attempt to perform an operation when the file is not
opened for that purpose.

16.  This feature facilities the supply of arguments
to the main() function.
 These arguments are supplied at the time of
invoking the program.
◦ C> exam data results
◦ Exam is the name of the file containing the program
to be executed ,data and results are the filenames
passed to the program as command-line arguments.

17. THANKYOU!!!