This document discusses files and file streams in C++. It covers the different stream classes like fstream, ifstream, and ofstream used for file input/output. It describes opening and closing files, reading/writing characters and objects to files, and different file modes. Example programs are provided to demonstrate reading from and writing to files using functions like get(), put(), read(), and write().

1. .
FILES IN C++

2. TITLES:
• Use of header file fstream.h
• Types of stream objects
• Open() and close() functions
• File mode constants
• Reading and writing characters from to disk
• Reading and writing objects from to disk

3. FILE STREAM:
• A file stream act as an interface between program and the files
• The stream that supplies data to the program is known as input stream
• The stream that receives data from the program is known as output stream
• Input stream
• read data data
I/P
• Output stream
• Write data data
O/P
ProgramDisk file

4. CLASSES FOR FILE STREAM OPERATIONS:
• Io stream file
• F stream file
ios
Stream buf O streamI stream
Io stream
If stream F stream Of stream File buf
F stream base

5. USING F STREAM.H:
• A stream is a sequence of bytes.
• It is general name given to a flow of data.
• Different streams are used to represent different kinds of data flow.
• ifstream class represents input disk files.
• Ofstream class represents output disk files.
• Fstream for both input and output

6. DIFFERENT CLASSES AND ITS FUNCTIONS:
class functions
File buf It sets the file buffers to read and write.
Member function : open(),close()
Fstream base This is the base class for fstream,ifstream
and ofstream classes.
Member function : All input and output
function open(),close()
ifstream It provide input operation for file.
Member function : get(),getline (),read
(),seekg (),tellg ()
ofstream It provide output operation for file
Member function : put (),write (),seekp (),tellp
()
fstream It is an input and output stream.

7. OPENING AND CLOSING FILES:
• Opening of files can be achieved in two ways:
1. using the constructor function of the stream class
syntax : stream stream object (“name of file name”);
2. using the function open()
syntax : stream stream object;
stream object . Open (“name of file name”);

8. TYPES OF FILES:
• Files are two types:
1. ASCII files or text files:
those files created by storing characters.
2.Binary file:
those files created by storing a block of memory.

9. THE CONCEPT OF FILE MODES:
• It describes how a file is to be used
1. To read from it.
2. To write to it.
3. To append it.
4. To read and write and so on..
syntax : stream object . Open (“file name”, file_mode);

10. TYPES OF FILES:
s.no File modes meaning Stream type
1. ios::in It opens file for
reading
Ifstream
2. ios::out It opens file for
writing
ofstream
3. ios::app It causes all output to
that file to be
appended to the end
ofstream
4. ios::ate It seeks to end-of-file
upon opening of the
file
ofstream
5. ios::trunc Delete contents of
the file if it exists
ofstream
6. ios::nocreate It causes the open ()
functions to fail if the
file does not already
exit.it will not create
a new file with that
ofstream

11. READING AND WRITING CHARACTERS FROM TO
DISK:
• The function put () and get () are used for manipulating a file
character by character.
• These function are members of ostream and istream
respectively
put() is used for output to the file.
get() is used for input from file.

12. #include <fstream.h>
Void main()
{
char ch;
ifstream infile (“out.txt”);
while (infile)
{
infile.get (ch);
cout << ch;
}
infile . Close();l
}
#include <fstream.h>
void main()
{
ofstream outfile (“out.txt”);
char str[]=“This is a text file”;
int i=0;
while (str[i])
outfile.put (str [i++]);
outfile.close ();
}
EXAMPLE PROGRAMS:
To create a file using put() To read a file using get()

13. READING AND WRITING CLASS OBJECTS FROM
TO DISK:
• The functions write() and read() are usually used to transfer a
block of data from and to the file.
• Write () is used for output to the file.
• Read () is used for input from file.

14. • To get the contents from the file
• It takes two arguments
i.e., a pointer to the block and
the size of the block
Eg : std file. Read
((char*&s,sizeof(student));
• It takes two arguments.
i.e., a pointer to the block and
the size of the block.
Eg : std file.write
((char*)&s,sizeof(student));
.
To write to the file To read the file

15. PROGRAM TO CREATE A STUDENT FILE:
#include<fstream.h>
Class student
{
private :
int regno,mark;
char name [20];
public :
void getdata ();
};
void student :: getdata ()
{
cout <<“n enter reg.number :”;
cin >> reg no;
cout <<“n enter name of students”;
gets (name);
cout <<“nenter marks:”;
cin >> marksw;
}

16. .
Void student :: display ()
{
cout << “n register number :”<<reg no;
cout << “n na,me of student :”<<name;
cout << “n marks :”<<marks;
}
Void main()
{
student ob;
fstream std file;
Std file.open (‘stud.dat”,ios :: in);
std file.read ((char*)&ob,sizeof(student));
while (std file)
{
ob.display();
std file.read((char*)&ob,sizeof(student));
}
std file.close();
}

17. OUTPUT:
• Open for reading only
• I/P POINTER
• Open for writing only
• O/P POINTER
• Open for append mode
H A I
H A I