Charming the Python: File Handling

#python #beginners

If coding tutorials with math examples are the bane of your existence, keep reading. This series uses relatable examples like dogs and cats.

File Handling

File handling allows you to create, read, update and delete files. I assume this is where CRUD comes from.

Opening a File

Using the open() function, you can create, read, and update files

#syntax
open('filename', mode)

Mode

mode		does...	if file doesn't exist...
`r`	read	default value, opens for reading	error if file doesn't exist
`a`	append	opens a file for appending	creates file if it doesn't exist
`w`	write	opens a file for writing	creates file if it doesn't exist
`x`	create	creates specified file	error if file already exists
`t`	text	default value, text mode
`b`	binary	binary mode, (e.g. images)

Reading a File

This first examples let's us look at the WHOLE file

file = open('./dogs.txt','r')
text = file.read(). # put a number as a parameter & get that many characters
print(text)

#output
allllllllllllllllllllllllllllllllllllllllllllllll the words of the file print here and blah blah blah...

you may also readlines() and read().splitlines()

Writing to a File

If you write a file that doesn't exist, it will create one. Here's an example.

with open('./dogs.txt','w') as f:
    f.write('text about dogs')

Append to a File

To append = add to the end
If I want to make my file include cats, here's what I'd do

with open('./dogs.txt','a') as f:
    f.write('and cats')

Now the file reads: "text about dogs and cats"

Deleting a File

import os
os.remove('./dogs.txt')

If the file doesn't exist, it can't remove it and will give an error. For this case, it may be good to use an if-else condition.

import os
if os.path.exist('./dogs.txt’):
    os.remove('./dogs.txt')
else:
    os.remove("file doesn't exist")

Series loosely based on

30 Days Of Python Challenge

Asabeneh ・ Nov 20 '19 ・ 1 min read

#python #javascript #react #mongodb

Top comments (5)

rhymes • Feb 21 '20 • Edited

Hi Vicki, nice notes!

I'm going to suggest the builtin module pathlib as well, which has an object oriented interface on path navigation and manipulation. You might find it helpful!