Python Data File Handling

operations on text file

A text file consists of a sequence of lines. A line is a sequence of characters, stored on permanent storage. In a text file, each line is terminated by a special character, known as End Of Line (EOL). Text file can be created using any text editor. Ex. Myfile.txt.

 

Opening a text file: Open ()

When we want to read or write a file, we must have to open is first. Open () function takes the name of a file as the first argument. The second argument indicates the mode of accessing the file.

Syntax:

<file variable>=open(file name, access mode)

Modes for opening a file:

read(r) : to read the file

write(w): to write the file

append(a):  to write at the end of file

 

Ex:

>>> f=open(‘myfile.txt’)

>>> print(f)

 

Output:

<_io.TextIOWrapper name='myfile.txt' mode='r' encoding='cp1252'>

 

 

Closing file: close()

Syntax:  file_Object.close()

Example:

f=open('myfile.txt')
print("The file which is to be open using the given command is:",f.name)
f.close()

Output:

The file which is to be open using the given command is: myfile.txt

 

Properties of File Object:

 

name: shows the file name of opened file

mode: shows Mode in which the file gets opened

readable: returns Boolean value, which indicates whether the file is readable or not

closed: returns Boolean value, which indicates whether the file is closed or not

 

Example:

f=open('myfile.txt', 'w')
print("Name of File:",f.name)
print("Mode of File:",f.mode)
print("File readable :",f.readable())
print("File closed:",f.closed)
f.close()
print("File closed:",f.closed, f.name)

 

 

Output:

Name of File: myfile.txt
Mode of File: w
File readable : False
File closed: False
File closed: True myfile.txt

 

Reading form a file:

We can read character data from text file by using the following read methods:

 

read(): To read the entire data from the file; starts reading from the cursor up to the end of the file.

Synatx:

file_Object.read()

Example:

The text file named myfile.txt is already stored in my local disk with the data shown in image.

CBSE file handling

 

f=open('myfile.txt', 'r')
data=f.read()
print(data)
f.close()

 

Output:

== RESTART: C:/Users/ATC/AppData/Local/Programs/Python/Python38-32/filehandling.py =
Hello,
Welcome to the CBSE class 12 students
Having computer science with python
You are learning Python file handling
>>>

read(n): To read ‘n’ characters from the file, starting from the cursor.

Example: Here we will read only first 21 characters from the file.

f=open('myfile.txt', 'r')
data=f.read(21)
print(data)
f.close()

 

Output:

Hello,
Welcome to the

 

 

readline(): To read only one line from the file; starts reading from the cursor up to, and including, the end of line character.

readlines(): To read all lines from the file into a list; starts reading from the cursor up to the end of the file and returns a list of lines.

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