2. File Handling
A file is a sequence of bytes on
the disk/permanent storage
where a group of related data is
stored.
File is created for permanent
storage of data.
3. File Handling
Types of File
There are two types of files:
Text Files- A file whose contents can be viewed using a text editor is
called a text
file. (.txt)
• A text file is simply a sequence of ASCII or Unicode characters.
• EOL (new line character i.e. enter) or internal translation occurs
• e.g. Python programs, contents written in text editors
Binary Files-(.dat)
• A binary file stores the data in the same way as as stored in the memory.
• No EOL or internal translation occurs( not converted into other form
becoz it is converted into computer understandable form i.e. in binary
format)
• Best way to store program information.
. e.g. exe files,mp3 file, image files, word documents
we can’t read a binary file using a text editor.
4. TEXT FILE
•Text files don’t have any specific encoding
and it can be opened in
normal text editor itself.
•Example:
•Documents: txt, RTF etc.
•Tabular data: csv, tsv etc.
5. BINARY FILE
• Non human readable
• Can open in normal text editor.
• but we can’t read the content present inside the file.
• That’s because all the binary files will be encoded in the
binary format, which can be understood only by a computer or
machine.
• For handling such binary files we need a specific type of
software to open it.
• For Example, We need Microsoft word software to open .doc
binary files.
• Likewise, you need a pdf reader software to open .pdf binary
files and you need a photo editor software to read the
image files and so on.
6. File Handling
File operations- adding, modifying, deleting, reading, writing,
appending data There are three steps to perform these operations:
Open the file.- Before any reading or writing operation of any
file , it
must be opened first
of all.
Process file- i.e perform read or write operation.
Close the file.-Once we are done working with the file, we should
close the
file. Closing a file releases valuable system resources.
In case we forgot to close the file, Python automatically close the file
when
program ends or file object is no longer referenced in the
program.
However, if our program is large and we are reading or writing multiple files
that can take significant amount of resource on the system. If we keep
opening
new files carelessly, we could run out of resources.
7. File Handling
open () - built in function
Syntax
file_object/file_handler = open(<file_name>, <access_mode>,< buffering>)
file_name = name of the file ,enclosed in double quotes.
access_mode= It is also called file mode. Determines the what
kind
of operations can be performed with file,like read,write etc.
If no mode is specified then the file will open in read mode.
8. File Handling
Opening file
F=open(“notes.txt”,”r”) #open a file in read mode and specified relative
path
F1=open(r“c:usershpnotes.txt”,”r”)
#open a file in read mode and specified absolute path(if file is stored in some other
folder/location
F1=open(“c:usershpnotes.txt”,”w”)
To specify absolute path of the file either use in
each subpath or use r before the path , then
python environment will consider it as a raw path
string nothing else
F1=open(r “c:usershpnotes.txt”,”r”)
This ‘r’ has no relation with file
mode
9. File Handling
File opening modes-
Sr.
No
Mode & Description
1 r - reading only.Sets file pointer at beginning of the file . This is the defaultmode.
2 rb – same as r mode but with binary file
3 r+ - both reading and writing. The file pointer placed at the beginning of the file.
4 rb+ - same as r+ mode but with binary file
5 w - writing only. Overwrites the file if the file exists. If not, creates a new file for writing.
6 wb – same as w mode but with binary file.
7 w+ - both writing and reading. Overwrites . If no file exist, creates a new file for R & W.
8 wb+ - same as w+ mode but with binary file.
9 a -for appending. Move file pointer at end of the file.Creates new file for writing,if not exist.
10 ab – same as a but with binary file.
11 a+ - for both appending and reading. Move file pointer at end. If the file does not exist, it
creates
a new file for reading and writing.
12 ab+ - same as a+ mode but with binary mode.
10. File Handling
The read() Method
It reads the entire file and returnsit contents
in the form of a string.
Reads at most size bytes or less if end of
file occurs.
if size not mentioned then read the entire file
contents.
f=open(“notes.txt”,”r
”) r=f.read()
print(r)
11. File Handling
Read characters from last
position
read([size]) method
It reads the no of bytes
f=open(“notes.txt”,”r
”) r=f.read(10)
print(r)
r1=f.read(15
) print(r1)
12. File Handling
Absolute Path
The absolute path is the full path to some place on your computer.
OR
It is the path mentioned from the top level of hierarchy.
OR
To access a given file or directory, starting from the root of the file system
For example: Absolute path: C:UsershpDesktopcsfunction.py
Path-
it is a sequence which gives us access to a file.
•
• It is an address or location
Relative Path
The relative path is the path to some file with respect to current working
directory
e.g. Relative path: “function.py”
or
“..function.py”
13. File Handling
The read() Method
It reads the characters.It returns the read
characters as string
f=open(“notes.txt”,”r
”) r=f.read()
print(r)
14. File Handling
The readline() Method
It reads the line.It returns the read lines as
string
f=open(“notes.txt”,”r
”) r=f.readline()
print(r)
15. File Handling
The readlines() Method
It reads the lines.It returns the read lines as
list
f=open(“notes.txt”,”r
”) r=f.readlines()
print(r)
16. File Handling
Read first 2 lines
It reads the lines.It returns the read lines as list
f=open(“notes.txt”,”r
”) r=f.readline()
print(r)
r1=f.readline(
) print(r1)
OR
readlines([si
ze]) method-
Read no of
lines from
file if size
is
mentioned
17. File Handling
The close() Method
close(): Used to close an open file..
f=open(“notes.txt”,”r”)
r=f.read()
print(r)
f.close()
• After using this method, an opened file will
be closed and a closed file cannot be read or
written any more.
18. File Handling
Program to display number of lines in a
file.
f=open(“c:usershp
notes.txt”,”r”)
r=f.readlines(
) d=len(r)
print(d)
f.close()
19. File Handling
write() and read() based program
f = open("a.txt", 'w')
line1 = 'Welcome to python'
f.write(line1)
line2="nRegularly visit pythonapsdk.blogspot.com"
f.write(line2)
f.close()
f = open("a.txt", 'r')
text = f.read()
print(text)
f.close()
OUTPUT
Welcome to
python
Regularly visit
pythonapsdk.blo
gspot.com
20. File Handling
Append content to a File
f = open("a.txt", 'w')
line = 'Welcome to
pythonapsdk.blogspot.com’
f.write(line)
f.close()
f = open("a.txt",
'a+') f.write("
nthanks") f.close()
f = open("a.txt",
'r') text = f.read()
print(text)
f.close()
A
P
P
E
N
D
C
O
D
E
21. File Handling
FLUSH()
It forces the writing of data on disc still pending in
buffer
f = open("a.txt", 'w')
line = 'Welcome to pythonapsdk.blogspot.com’
f.flush()
D=“class
xii”
f.write(D)
f.write(“sect
ion L”)
f.flush()
f.close()
22. File Handling
File Pointer
It tells the current position in the file
where writing or reading
will take place.(like a bookmark in a
book)
The tell() method of python tells us the current
position within the file,where as The seek(offset[,
from]) method changes the current file position. If
from is 0, the beginning of the file to seek. If it is set
to 1, the current position is used . If it is set to 2 then
the end of the file would be taken as seek
position. The offset argument indicates the number
of bytes to be moved.
23. f = open("a.txt", 'w')
line = 'Welcome to
pythonapsdk.blogspot.com' f.write(line)
f.close()
f = open("a.txt", 'rb+')
print(f.tell())
print(f.read(7)) # read seven characters
print(f.tell())
print(f.read())
print(f.tell())
f.seek(9,0) # moves to 9 position from
begining
print(f.read(5))
f.seek(4, 1) # moves to 4 position from
current location
print(f.read(5))
f.seek(-5, 2) # Go to the 5th byte before the
end print(f.read(5))
File handling
![File Handling
Read characters from last
position
read([size]) method
It reads the no of bytes
f=open(“notes.txt”,”r
”) r=f.read(10)
print(r)
r1=f.read(15
) print(r1)](https://image.slidesharecdn.com/filehandling-250327032705-6c30dba3/85/this-is-about-file-concepts-in-class-12-in-python-text-file-binary-file-csv-file-11-320.jpg)
![File Handling
Read first 2 lines
It reads the lines.It returns the read lines as list
f=open(“notes.txt”,”r
”) r=f.readline()
print(r)
r1=f.readline(
) print(r1)
OR
readlines([si
ze]) method-
Read no of
lines from
file if size
is
mentioned](https://image.slidesharecdn.com/filehandling-250327032705-6c30dba3/85/this-is-about-file-concepts-in-class-12-in-python-text-file-binary-file-csv-file-16-320.jpg)
![File Handling
File Pointer
It tells the current position in the file
where writing or reading
will take place.(like a bookmark in a
book)
The tell() method of python tells us the current
position within the file,where as The seek(offset[,
from]) method changes the current file position. If
from is 0, the beginning of the file to seek. If it is set
to 1, the current position is used . If it is set to 2 then
the end of the file would be taken as seek
position. The offset argument indicates the number
of bytes to be moved.](https://image.slidesharecdn.com/filehandling-250327032705-6c30dba3/85/this-is-about-file-concepts-in-class-12-in-python-text-file-binary-file-csv-file-22-320.jpg)
