FILE HANDLING
Ajay Godwal
PGT CS , KV Ballia
Need of File
If something is to be stored in our
computer in permanent form then we
create a file in suitable
format(jpeg,png,mp3,txt,doc) and this
files is stored in any secondary storage
device.
File Handling
 It is collection of data, stored on any secondary storage device
 We need data to be written, modified, deleted and read from a physical storage like
a disk by using a programming language. This is quite helpful in storing data for
future use.
 Python too provides several features to perform various operations on disk files
using built-in functions.
Types of Files
 Text files: In this type of file, Each line of text is terminated
with a special character called EOL (End of Line), which is
the new line character (‘\n’) in python by default.
 Binary files: In this type of file, there is no terminator for a
line and the data is stored after converting it into machine
understandable binary language.
 CSV A comma-separated values file is a delimited text file
that uses a comma to separate values. Each line of the file is a
data record. Each record consists of one or more fields,
separated by commas. The use of the comma as a field
separator is the source of the name for this file format.
nm=input (“Enter Your Text”)
User Input
Output
print(nm)
nm=“we are learning file handling”
Primary Storage
RAM
input()
file
write()
Primary Storage
RAM
User Input Output
Print()
var
Read()
myFile
……………
…………….
Secondary Storage
Ex. HardDisc
Text File in Python
To open a file in different modes
file=open(filename,mode)
r
w
Opens a file for reading only . The file pointer is placed at the beginning of the file.
Opens a file for writing only. Overwrites the file if the file exists. If the file does not exist,
creates a new file for writing.
w+
Opens a file for both writing and reading. Overwrites the existing file if the file exists. If the
file does not exist, it creates a new file for reading and writing.
r+
Opens a file for both reading and writing.
a
Opens a file for appending. The file pointer is at the end of the file if the file exists. That is,
the file is in the append mode. If the file does not exist, it creates a new file for writing.
a+
Opens a file for both appending and reading. The file pointer is at the end of the file if the
file exists. The file opens in the append mode. If the file does not exist, it creates a new file for
reading and writing..
x
open for exclusive creation, failing if the file already exists
NOTE rb,rb+,wb,wb+,ab+ are other modes related with binary files
Writing/append into file
Open a file
file=open(“myfile.txt”,”w”)
Take User
Input
str=input(“Enter Your
Text”)
Write into
file
Demo Prg in Jupyter
file.write(str)
Use mode “a” to append more
Close the
file
file.close()
Reading From File
Open a file
file=open(“myfile.txt”,”r”)
Read From
File
str=file.read()
Print on
Screen
print(str)
Close the
file
file.close()
Demo Prg in Jupyter
read(n)-to read n char from a file
supermom.txt
Super Mom
Mom, you're a wonderful mother,
So gentle, yet so strong.
The many ways you show you care
Always make me feel I belong.
You're patient when I'm foolish;
You give guidance when I ask;
It seems you can do most anything;
You're the master of every task.
readline() –to read a line at at time
supermom.txt
Super Mom
Mom, you're a wonderful mother,
So gentle, yet so strong.
The many ways you show you care
Always make me feel I belong.
You're patient when I'm foolish;
You give guidance when I ask;
It seems you can do most anything;
You're the master of every task.
readlines()-stores in list of string
write() & writelines()
 write() writes a string str to the file
 writelines() writes a sequence of strings to the file. The sequence can be any
iterable object producing strings, typically a list of strings
flush()
flush()-write() writes a string str to the fileDue to buffering, the string may not actually show up in the file until the
flush() or close() method is called.it forces the writing of data on disc still pending in output buffer
User Input Output
buffer
file
flush()
Write()
Primary Storage
RAM
file.write(“one”)
file.write(“two”)
file.flush()
file.write(“three”)
file.write(“four”)
File.close()
myFile
……………
…………….
Secondary Storage
Ex. HardDisc
seek() & tell()
 seek() to set
position of file
pointer at a
specific byte no
 tell() to access
position of file
pointer
Practice Qus-2/3 Marks
Practice Qus-2/3 Marks
 Thank You