Variables names:

• Variables names can contain only letters, numbers, and/or underscores.
• Variables names can't start with a number.

Define a variable: a = "Hello" print(a) # ==> Hello
Multiple assignment: x, y , z = 1, 2, 3 a, b , c = 'hello', 'python', '!'

To comment a line or part of a line, use the hash mark character (#). #this is a comment x = 1 # this another comment

Integers: 1, 2, ...
Floats, 1.0, 2.0, ...
Operations: +, -, *, /, \%, ** (exponents)

Using underscores between digits in numeric literals: i = 1_000_000 print(i) # ==> 1000000
Modulo operator: i = 5 % 2 print(i) # ==> 1

a = "This is a valid string" b = "This is a 'valid' string" c = 'This is a valid string' d = 'This is a "valid" string'
Changing string case: #The title() function changes each word of a string in title case (begins with a capital letter) print('hello python'.title()) # ==> Hello Python #The upper() function changes a string to all uppercase print('hello python'.upper()) # ==> HELLO PYTHON #The lower() function changes a string to all lowercase print('HELLO PYTHON'.lower()) # ==> hello python
Formating a string (f-strings):
To use a variable or a function inside a string, place the letter f before opening quotation mark.
Inside the string put any variable or function you want to use and surround it with braces. x='hello' y='python' z=f'message: {x} {y.title()}' print(z) # ==> message: hello Python
Adding whitespace to strings with tabs (\t) or newlines (\n): print("hello\n\n\t\tpython") hello python
Stripping whitespace: x = ' hello python ' #use strip() function to remove whitespace from the beginning (left) and the end (right) of a string. print(f'"{x.strip()}"') # ==> "hello python" #use lstrip() function to remove whitespace from the beginning (left) of a string. print(f'"{x.lstrip()}"') # ==> "hello python " #use rstrip() function to remove whitespace from the end (right) of a string. print(f'"{x.rstrip()}"') # ==> " hello python"
Removing prefixes and suffixes: x = "hello python" print(f'"{x.removeprefix("hello")}"') # ==> " python" print(f'"{x.removesuffix("python")}"') # ==> "hello "
Split words: words = 'hello python 3'.split() print(f'Number of words: {len(words)}') # ==> Number of words: 3 for word in words: print(f'word: {word} | length: {len(word)}') Number of words: 3 word: hello | length: 5 word: python | length: 6 word: 3 | length: 1
Split lines: lines = 'hello\n\n\t\tpython'.splitlines() for line in lines: print(f'line: {line.strip()}') line: hello line: line: python
Convert string to int: i = int('1') print(i) # ==> 1

Parsing a string date using a specific format: from datetime import datetime date = datetime.strptime('05/08/2023 01-16-26 PM', '%d/%m/%Y %I-%M-%S %p') print(date) #==> 2023-08-05 13:16:26
Date and time formating:

• %d: Day of the month (01 - 31)
• %m: Month (01 - 12)
• %y: Two-digit year (23, ...)
• %Y: Four-digit year (2023, ...)
• %I: Hour, in 12-hour format (00 - 12)
• %H: Hour, in 24-hour format (00 - 23)
• %p: AM|PM
• %M: Minutes (00 - 59)
• %S: Seconds (00 - 59)
• %A: Weekday name (Monday, ...)
• %B: Month name (January, ...)