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Read Content of File

1.Read Contents

  • open() method return a file object and file object have a method called read() for reading the content of an file.

Syntax:

fillez=open("file name with extenssion","r")
data=filez.read()

mylog.txt contains

Hi, hello i am from python file.

Example:

fil=open("mylog.txt","r")
content=fil.read()
print(content)

Output:

Hi, hello i am from python file.

How to read some content from a file

  • for read() method you can pass an integer length of character (a number that shows how many characters do you want to read)

  • after reading statement python cursor will position according to given input to read() function.

  • we can manipulate the python file cursor position using seek() function

  • tell() function is used to getting the current position of the cursor in file.

Syntax:

fileobject.read(length)

mylog.txt contains

Hi, hello i am from python file.

Example: Read first 2 character from a mylog.txt file

#Initialize file for read purpose
fil=open("mylog.txt","r")

#Read 2 byte content of file
content=fil.read(2)

print(content)
#Result:Hi

Output:

Hi

mylog.txt contains

Hi, hello i am from python file.

Example:

# initialize file for reading purpose
fil=open("mylog.txt","r")

#get cursor position
cur=fil.tell()
print("Current Position of Cursor")
print(cur)
#Result:0

#Read 2 character from file
fil=open("mylog.txt","r")
content=fil.read(2)
print("\nRead 2 character from file")
print(content)
#Result:Hi

#Now get updated  cursor position
cur=fil.tell()
print("\nupdated  cursor position")
print(cur)
#Result:2

#Read next 7 character from file
content=fil.read(7)
print("\nRead next 7 character from file")
print(content)
#Result: , hello

#now get the updated cursor position
cur=fil.tell()
print("\nupdated cursor position")
print(cur)
#Result:9

#now move cursor to 0 position which is start of file
print("\nnow move cursor to 0 position which is start of file")
fil.seek(0)

#Print Current Cursor  Position
print("\n Current Cursor Position")
print(fil.tell())

Output:

Current Position of Cursor
0

Read 2 character from file
Hi

updated  cursor position
2

Read next 7 character from file
, hello

updated cursor position
9

now move cursor to 0 position which is start of file

 Current Cursor Position
0

How to read a line from a given file

  • readline() function is used to read a line from a file.
  • By calling readline() three times, you can read the three first lines.

Syntax:

fileobject.readlines()

Consider mydata.txt file contains

First line data 1
Second line data 2
Third line data 3
Fourth line data 4

Example:

#Create File Object For Reading Purpose
fil=open("mydata.txt","r")

#Read First File From File
firstline=fil.readline()

#Print First File
print(firstline)

Output:

First line data 1

How to read all lines from a file

  • readlines() is return list object with every line as an element

Syntax:

fileobj=open(filename,"r")
data=fileobj.readlines()

mydata.txt file contains

First
Second
Third

Example:

#initialize file for reading purpose
fil=open("mydata.txt","r")

#read all lines and Store it in list
lines=fil.readlines()

#Print All Lines List
print(lines)

Output:

['First\n', 'Second\n', 'Third']

Read all file using "with" statement

File mylog.txt contains

Hi, hello i am from python file.

Example

#Read File using  with loop
with open("mylog.txt","r") as fil:
  content=fil.read()
  print(content)

Output:

Hi, hello i am from python file.

How to use for loop for reading all multi-line

file mydata.txt contains

First line data 1
Second line data 2
Third line data 3
Fourth line data 4

Example:

#Initilize file object
fil=open("mydata.txt","r")

#Use for loop Print line by line 
for line in fil:
  print(line)

Output:

First line data 1

Second line data 2

Third line data 3

Fourth line data 4