Python Programming: Summary

1. Variables

A variable is a name used to store data in a program. In Python, we create a variable by using =

Example: x = 42

Python is dynamically typed, so Python automatically knows the type of data stored in a variable.

Common variable types :

• Int : whole numbers such as 10

• Float : decimal numbers such as 3.14

• Str : text such as "Hello"

• Bool : True or False

• List : an ordered and changeable collection such as [1, 2, 3]

• Tuple : an ordered collection that can’t be changed such as (4, 5)

• Dict : stores data as key value pairs such as {‘name': 'Alice', 'age': 25}

• Set : a collection of unique values such as {1, 2, 3}

• None : represents no value

Python is case sensitive, so myVar and myvar are different. A variable name can’t start with a number.

2. Basic Operations

Python has several types of basic operations.

Arithmetic operations are used for calculations :

• + : Addition

• - :  Subtraction

• * :  Multiplication

• / : Division

• //: Floor division

• % : Modulus or remainder

• **: Exponentiation or power

Example: 17 // 5 gives 3, while 17 % 5 gives 2.

Assignment operations are used to give or update values :

• = :  Assigns a value

• += :  Adds and updates

• -= :  Subtracts and updates

• *= :  Multiplies and updates

• /= :  Divides and updates

Example: x = 5 and x += 3 makes x equal to 8.

Comparison operations compare two values :

• == : Equal

• != : Not equal

• > : Greater than

• < : Less than

• >= : Greater than or equal

• <= : Less than or equal

The result is usually True or False.

Logical operations are used with conditions :

• And : both conditions must be true

• Or : at least one condition must be true

• Not : changes True to False or False to True

Membership operations check whether something exists in a collection :

• In : checks if a value exists

• Not in : checks if a value does not exist

3. String Manipulation

A string is text made up of characters. String manipulation means working with and changing text.

Important string operations include:

• Concatenation : joining strings together using +

• String formatting : creating text using variables, often with an f-strings

• len() : finds the number of characters

• Indexing : gets a character from a specific position

• Slicing : gets part of a string

• .upper() : changes text to uppercase

• .lower() : changes text to lowercase

• .strip() : removes spaces at the beginning and end

• .replace() : replaces one piece of text with another

• In : checks whether a word or character exists in a string

• .split() : separates a string into smaller parts or words

Key Points to Remember!

Variables store data.
Data types describe what kind of data is stored.
Operators perform calculations, comparisons and logical operations.
Strings are used for text and can be changed or analyzed using different methods.