EDS 217 Cheatsheet

Python Basics

Python Basics Cheatsheet

Variables and Data Types

Declaring Variables

  • Variables are containers for storing data values.
  • Python has no command for declaring a variable: it is created the moment you first assign a value to it.
Code 
x = 5
name = "Alice"

Data Types

  • Python has various data types including:
    • int (integer): A whole number, positive or negative, without decimals.
    • float (floating point number): A number, positive or negative, containing one or more decimals.
    • str (string): A sequence of characters in quotes.
    • bool (boolean): Represents True or False.
Code 
age = 30        # int
temperature = 20.5  # float
name = "Bob"    # str
is_valid = True # bool

Basic Operations

Arithmetic Operators

  • Used with numeric values to perform common mathematical operations:
Operator Description
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulus
** Exponentiation
// Floor division

Example Usage

Code 
x = 10
y = 3
print(x + y)  # 13
print(x - y)  # 7
print(x * y)  # 30
print(x / y)  # 3.3333
print(x % y)  # 1
print(x ** y) # 1000
print(x // y) # 3
13
7
30
3.3333333333333335
1
1000
3

Logical Operators

  • Used to combine conditional statements:
Operator Description
and Returns True if both statements are true
or Returns True if one of the statements is true
not Reverse the result, returns False if the result is true

Example Usage

Code 
x = True
y = False
print(x and y)  # False
print(x or y)   # True
print(not x)    # False
False
True
False

Strings

  • Strings in Python are surrounded by either single quotation marks, or double quotation marks.
Code 
hello = "Hello"
world = 'World'

# Modern approach (f-strings) - PREFERRED
print(f"{hello} {world}")  # Hello World

# Older approach (string concatenation) - you'll see this in code
print(hello + " " + world)  # Hello World
Hello World
Hello World
  • Strings can be indexed with the first character having index 0.
Code 
a = "Hello, World!"
print(a[1])   # e
e
  • Slicing strings:
Code 
b = "Hello, World!"
print(b[2:5])  # llo
llo

Printing and Commenting

Code 
# This is a comment
print("Hello, World!")  # Prints Hello, World!
Hello, World!

This cheatsheet covers the very basics to get you started with Python. Experiment with these concepts to understand them better!