File:- A file is a bunch of bytes stored on some storage
devices which can be read, write according to the
requirement.
Why there is need of file handling?
File help us to store the data permanently , which can
be retrieved for future use.
Types of files:-
1. Text files
2. Binary files
Text files:
● Stores information in ASCII or Unicode
characters , so translation takes place.
● Each line of text terminated with a special
character known as EOL(end of line)
● Extension for text file is .txt.
● Text file is default mode of file.
Binary files:-
● Contains information in the same format as it is
stored in the memory.
● No translation takes place.
● There is no delimiter for a line i.e EOL.
● More secure.
● Extension for binary file is .dat
File Access Modes
Mode Description
r Open file for reading only. This is the default mode.
w Open file for writing only. Overwrites the file if
already exists, else creates a new file.
a Opens a file for appending. The file pointer is at
the
end of the file if the file exists. If file does not
exist,
it creates a new file for writing .
a+ Opens a file for both appending and reading.
r+ Opens a file for both reading and writing.
w+ Opens a file for both reading and writing.
rb Open file for reading only in binary format. This is
the default mode.
rb+ Opens a file for both reading and writing in
binary
format.
wb+ Opens a file for both reading and writing in
binary
format.
ab Opens a file for appending in binary format.
ab+ Opens a file for appending and reading in binary
format.
Data File Operations
● Opening a File
● Performing operations
● Closing a file
Different types of operations can be:-
● Creating a file
● Displaying record from a file
● Appending data in a file
● searching data in a file
● Deleting data from a file
How to open a text file
FileObject=open<filename>
Or
FileObject=open<filename>,<mode>
For example
Fobj=open(“text.txt”,w)
Fobj=open(“c:\users\neena\n1.txt”,w)
Fobj=open(r, ‘c:\users\neena\n1.txt’,w)
File access modes
By default mode is read
How to write data in a file?
There are two methods to write in a file:-
● write()
● writelines()
Whenever we write in a file there are two possibilities
1. File does not exist
2. File already exists
If file does not exist , it will create a new file.
If file exists, it will overwrite the data in the file if it is in
write mode
Write() method
● It takes a string and write it in the file.
● For storing data with EOL character we have to
add ‘\n’ character to the end of the string
● For storing numeric value , we have to either
converted into string using str() or write in quotes.
For example
#To create a file using write method
f=open("text2.txt","w")
f.write("hello\n")
f.write("how r u\n")
f.write("text file\n")
Text file
Program file
Open “text2.txt” in notepad
When we remove”\n” from a file
#To create a file using write method
f=open("text2.txt","w")
f.write("hello")
f.write("how r u")
f.write("text file")
f.close()
output
Writelines() method
● It used to write sequence data types in a file
like(string, list and tuple etc).
● We have to give “\n”
#File creation using writeln method
f= open("list.txt","w")
list=["python\n","physics\n","chemistry\n","maths\n","english\n"]
f.writelines(list)
tuple=("83","44","46","45","301")
f.writelines(tuple)
f.close()
Output
Value of tuple in
single line because
there is no “\n”
#TO ADD TWO NUMBERS AND STORE IN A FILE
f=open("sum.txt",'w')
num1=int(input("enter number1"))
num2=int(input("enter number2"))
sum=num1+num2
f.write("\nnum1= "+str(num1))
f.write("\tnum1= "+str(num1))
f.write("\tsum of two numbers= "+str(num1))
f.close()
output
num1= 34 num1= 34 sum of two numbers= 90
Reading data from a file
There are three methods to read from a file
read()
● Reads at most n bytes. If no n is specified , reads
the entire file.
● Returns the read bytes in the form of a string
● Syntax is:
● <fileobject>.read([n])
#TO read an entire file at a time
f=open("topic.txt",'r')
data=f.read()
print(data)
f.close()
output
>>>
============================================================= RESTART: C:/Users/Neena/
Desktop/notes/notes/file-handling/read.py
============================================================
File:- A file is a bunch of bytes stored on some storage devices
Why there is need of file handling?
File help us to store the data permanently , which can be retrieved for future use.
Types of files:-
1. Text files
2. Binary files
To read specific number of bytes
#TO read specific number of bytes from a file
f=open("topic.txt",'r')
data=f.read(10)
print(data)
data=f.read(10)
print(data)
f.close() Original content of a file “topic.txt”
output File:- A file is a bunch of bytes stored on some storage
devices
File:- A f Why there is need of file handling?
File help us to store the data permanently , which can be
ile is a b retrieved for future use.
Types of files:-
1. Text files
2. Binary files
Readline()
● Reads a line of input, if n is specified reads at
most n bytes.
● Returns the read bytes in the form of a string
ending with’\n’ character.
● Returns a blank string if no more bytes are left for
reading in the file.
● Syntax:<fileobject>.readline()
#TO read a line form a file
f=open("topic.txt",'r')
data=f.readline()# read single line from a file
print(data)
f.close()
output
File:- A file is a bunch of bytes stored on some storage devices
#TO read number of characters form a line
f=open("topic.txt",'r')
data=f.readline(100)# read n number of characters from a line
print(data)
f.close()
output
File:- A file is a bunch of bytes stored on some storage devices
Readlines()
● Reads all the lines of a text file.
● Returns in the form of list.
Syntax:-
<fileobject>.readlines()
#TO read all lines form a file
f=open("topic.txt",'r')
data=f.readlines()
print(data)
f.close()
output
['File:- A file is a bunch of bytes stored on some storage devices\n',
'Why there is need of file handling?\n',
'File help us to store the data permanently , which can be retrieved
for future use.\n',
'Types of files:-\n', '1.\tText files\n',
'2.\tBinary files\n']
