Python - File Handling

File handling is use to store the data in a file instead of just displaying it. Python has several functions for creating, reading, writing, updating, and deleting files.

The open() function is used to open the file. The open() function takes two parameters; filename, and mode.

f = open("anyfilename.txt")

There are four different methods (modes) for opening a file:

"r" - Read - Default value. Opens a file for reading, error if the file does not exist
"w" - Write - Opens a file for writing, creates the file if it does not exist
"a" - Append - Opens a file for appending, creates the file if it does not exist
"x" - Create - Create a file, returns an error if the file exist

In addition you can specify if the file should be handled as binary or text mode

"t" - Text - Default value. Text mode
"b" - Binary - Binary mode (e.g. images)

f = open("anyfilename.txt","rt")

f = open("anyfilename.txt", "x")

File methods:

1. open() - open the file
2. close() - close the file. It is a good practice to always close the file when you are done with it.
3. read() - reading the content of the file
4. read(5) - read only 5 characters
5. readline() - return one line
6. write() - write contents in a file
7. remove() - remove the file

Example 1: Open the file and read its content

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

If the file is located in a different location, you will have to specify the file path:

f = open("D:\\myfolder\\myfile.txt", "r")
print(f.read())
f.close()

By default the read() method returns the whole text, but you can also specify how many characters you want to return:

f = open("myfile.txt", "r")
print(f.read(5))
f.close()

Example 2: return one line by using the readline() method

f = open("myfile.txt", "r")
print(f.readline())
f.close()

By calling readline() two times, you can read the first 2 lines:

f = open("myfile.txt", "r")
print(f.readline())
print(f.readline())
f.close()

Read the whole file, line by line using for loop:

f = open("myfile.txt", "r")
for x in f:
    print(x)
f.close()

Write() function is use to write the content in a file, if file doesnot exists it create it, if file exits, it remove its contents and write it (overwrite the contents)

Example : Write contents in a file

f = open("myfile.txt", "w")
f.write("Write text using python write() function")
f.close()

Example : Write contents in a file and read it

f = open("myfile.txt", "w")
f.write("Write text using python write() function")
f.close()

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

Example : Append contents in a file and read it

f = open("myfile.txt", "a")
f.write("Add more contents using write function with append mode")
f.close()

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

You can also delete a file using Python remove() function. To delete a file, you must import the OS module.

import os
os.remove("myfile.txt")

import os
try:
    os.remove("myfile.txt")
    print("file deleted")
except:
    print("file not found")

To avoid getting an error, you might want to check if the file exists before you try to delete it:

import os
if os.path.exists("demofile.txt"):
  os.remove("demofile.txt")
else:
  print("The file does not exist")

To delete an entire folder, use the os.rmdir() method. You can only remove empty folders.

import os
os.rmdir("myfolder")