Python Fundamentals

Statements

A Statement is a complete instruction that Python executes to perform an action. It represents a single unit of execution.

Common Types of Statements:

• Assignment Statement: Used to store values in variables (e.g., x = 10).
• Input/Output: Statements like print() or input().
• Control Statements: Conditional (if/else) and Loop (for/while) structures.

# Examples of statements
x = 10              # Assignment
print(x)            # Output action
if x > 5:           # Conditional logic
    print("Large")

Expressions

An Expression is a combination of variables, constants, and operators that produces a specific value. It always returns a result.

Types of Expressions:

• Arithmetic: Uses math operators (10 + 3).
• Relational: Returns boolean results (a > b).
• Logical: Combines conditions (a and b).

Evaluation Process

Evaluation is the process by which Python calculates the final value of an expression. Python uses specific rules to ensure consistency.

Core Evaluation Rules:

• Operator Precedence: Decides priority (Multiplication before Addition).
• Associativity: Determines the order for same-level operators.
• Left-to-Right: Most operations are evaluated in this direction.

# Evaluation Example: 10 + 2 * 3
# 1. 2 * 3 is evaluated first (6)
# 2. 10 + 6 is evaluated second (16)
# Result: 16

Debugging Errors

Debugging is the systematic process of finding and fixing errors within a program to make it work correctly.

Common Types of Errors:

Effective Debugging Methods:

• Read Error Messages: Python tells you where the mistake is.
• Print Debugging: Use print() to check values during execution.
• Logic Check: Review your code step-by-step to find logic flaws.