The os Library , List a file, Create a folder, Renames a file

The os Library

Today's lesson is going to use the os library to create folders and navigate around them.

Previously, we've used os to clear the screen.

Here are a few other things that it can do:

List a file

👉 listdir() will allow you to list all the files:

import os

print(os.listdir()) # Lists all the files in the current directory. Useful for checking that a file is in the folder we think it is.

files = os.listdir()

if "quickSave.txt" not in files:

print("Error: Quick Save not found.")

#Checks if a file is in a directory and outputs an error if not.

Create a folder
👉 Try this code with os.mkdir():

import os

os.mkdir("Hello") # Creates a folder called 'Hello'

Renames a file

👉 os.rename() takes 2 arguments: the file to rename and the new name.

import os
os.rename("myname.txt", "NEW.o")

Comments

WHAT IS Nesting

WHAT IS Nesting Nesting is where we put an if statement within an if statement using the power of indenting. The second if statement within the first if statement must be indented and its print statement needs to be indented one more time. EXAMPLE:

IF AND ELSE STATEMENT

If Statements These statements are a bit like asking a question. You are telling the computer: if something is true, then do this specific block of code. Double equals ( == ) is asking the computer to compare if these two things are exactly the same. EXAMPLE : myName = input("What's your name?: ") if myName == "David": What is else? IF the condition is not met with the if statement, then we want the computer to do the else part instead. Likewise, if the condition is met in the if statement, then the else bit is ignored by the computer. The else statement must be the first thing unindented after the if statement and in line with it EXAMPLE : myName = input("What's your name?: ") if myName == "David": print("Welcome Dude!") print("You're just the baldest dude I've ever seen...

FOR LOOP , RANGE

FOR LOOP A while loop is perfect to use when we don't know how many times we want the loop to repeat. If we have an idea of how many times we want the loop to repeat, we can use a for loop to loop code in exactly the same way the while loop did. EXAMPLE : for counter in range(10): print(counter) RANGE The range function creates a list of numbers in the range you create. If you only give it one number, it will start at 0 and move to a state where the final number is one less than the number in the brackets. In this case, the final number would be 9 . EXAMPLE : total = 0 for number in range(100) : total += number print(total)

PYTHON SYNTAX

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