Week 1: Python Syntax Basics

Total Words: ~1,300

What is Python Syntax?

Python syntax refers to the set of rules that define how Python code is written and structured. Unlike many programming languages, Python emphasizes readability and simplicity, using indentation (whitespace) to define code blocks instead of braces {}.

Key characteristics of Python syntax:

Indentation: Code blocks like loops, functions, and conditionals are defined by consistent indentation (4 spaces recommended).
Case sensitivity: variable and Variable are treated as different names.
Comments: Use # for single-line comments and ''' or """ for multi-line comments.

Example:

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# This is a comment

if 5 > 2:

print("Five is greater than two!") # Indented block

Variables and Data Types

Variables

Variables store data values. Python uses dynamic typing, meaning you don’t need to declare a variable’s type explicitly.

Syntax:

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variable_name = value

Example:

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name = "Alice"

age = 25

is_student = True

Basic Data Types

Type	Description	Example
int	Integer values	10, -5
float	Decimal values	3.14, -0.5
str	Text (enclosed in quotes)	"Hello", 'Python'
bool	Boolean (True/False)	True, False
NoneType	Represents absence of value	None

Type Checking:

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print(type(age)) # Output: <class 'int'>

print(type(is_student)) # Output: <class 'bool'>

Basic Operations

Arithmetic Operators

Operator	Description	Example
+	Addition	5 + 3 → 8
-	Subtraction	10 - 2 → 8
*	Multiplication	4 * 3 → 12
/	Division	10 / 2 → 5.0
**	Exponentiation	2 ** 3 → 8
%	Modulus (remainder)	10 % 3 → 1

String Operations

Concatenation: Combine strings with +.
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greeting = "Hello, " + "Alice!" # "Hello, Alice!"
Repetition: Repeat strings with *.
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line = "-" * 20 # "--------------------"

Comparison Operators

Operator	Description	Example
==	Equal to	5 == 5 → True
!=	Not equal to	3 != 5 → True
>	Greater than	10 > 5 → True
<	Less than	3 < 2 → False

Logical Operators

Operator	Description	Example
and	Both conditions true	(5 > 2) and (3 < 5) → True
or	At least one condition true	(5 > 10) or (3 < 5) → True
not	Inverts the result	not (5 == 5) → False

Input and Output

Getting User Input

Use input() to read user input (returns a string):

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name = input("Enter your name: ")

age = int(input("Enter your age: ")) # Convert to integer

Printing Output

Use print() to display output:

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print("Hello,", name)

print(f"You are {age} years old.") # f-string (formatted string)

Common Mistakes & Troubleshooting

Indentation Errors:
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if 5 > 2:

print("Hello") # ERROR: Missing indentation
Fix: Indent code blocks consistently.
Incorrect Variable Names:
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2nd_name = "Alice" # ERROR: Starts with a number
Fix: Use second_name instead.
Type Errors:
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age = "25"

print(age + 5) # ERROR: Can't add string and integer
Fix: Convert types explicitly: print(int(age) + 5).
Forgetting Quotes for Strings:
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message = Hello # ERROR: Hello is undefined
Fix: Use message = "Hello".