Python Statements

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1. What is a Statement?

• A statement is a unit of code that performs an action or a task.
• Statements can include variable assignments, function calls, loops, conditionals, and more.
• Every line of code in Python is typically a statement.

x = 10                # Assignment statement
print("Hello")        # Function call statement
if x > 5:            # Conditional statement
    print("x is greater than 5")

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2. Types of Statements

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1. Assignment Statements

• Used to assign a value to a variable.
• The = operator is used for assignment.

name = "Raj"          # Assign a string to a variable
age = 25              # Assign an integer to a variable
is_student = True     # Assign a Boolean value

• Multiple Assignments:
  a, b, c = 1, 2, 3    # Assign multiple values at once
  x = y = z = 10       # Assign the same value to multiple variables
  

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2. Expression Statements

• Any expression becomes a statement when it is used on its own.
• Examples include arithmetic operations, function calls, etc.

10 + 20               # Arithmetic expression (but not useful as a standalone statement)
print("Hello, Ram!")  # Function call statement

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3. Conditional Statements (if, elif, else)

• Used to make decisions based on conditions.
• Keywords: if, elif, else.

age = 20
if age >= 18:
    print("Ram is eligible to vote.")
elif age >= 16:
    print("Ram can get a learner's license.")
else:
    print("Ram is too young.")

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4. Loop Statements (for, while)

• Used to repeat a block of code multiple times.
• Keywords: for, while.

• For Loop:
  names = ["Raj", "Ram", "Anand", "Bala"]
  for name in names:
      print(f"Hello, {name}!")
  
• While Loop:
  count = 0
  while count < 5:
      print(f"Count: {count}")
      count += 1
  

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5. Function Definition Statements (def)

• Used to define reusable blocks of code.
• Keyword: def.

def greet(name):
    print(f"Hello, {name}!")

greet("Karthik")  # Function call statement

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6. Import Statements

• Used to import modules or specific functions/classes from modules.
• Keyword: import.

import math                     # Import the entire math module
from datetime import date       # Import only the date class from datetime

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7. Control Flow Statements (break, continue, pass)

• Used to control the flow of loops or conditionals.
• Keywords: break, continue, pass.

• Break:
  for i in range(10):
      if i == 5:
          break  # Exit the loop when i is 5
      print(i)
  
• Continue:
  for i in range(10):
      if i % 2 == 0:
          continue  # Skip even numbers
      print(i)
  
• Pass:
  if x > 10:
      pass  # Placeholder for future code
  

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8. Return Statements

• Used in functions to return a value to the caller.
• Keyword: return.

def add(a, b):
    return a + b

result = add(5, 10)  # result = 15

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9. Exception Handling Statements (try, except, finally)

• Used to handle errors and exceptions in code.
• Keywords: try, except, finally.

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Execution complete.")

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3. Compound Statements

• Statements that contain other statements, such as loops, conditionals, and function definitions.
• They are often indented to define blocks of code.

if x > 10:
    print("x is greater than 10")  # Block of code under if
    print("This is part of the if block")

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4. Simple vs Compound Statements

• Simple Statements: Single-line statements that perform a single task.
  x = 10
  print("Hello")
  
• Compound Statements: Multi-line statements that contain blocks of code.
  if x > 10:
      print("x is greater than 10")
      print("This is a compound statement")
  

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5. Additional Examples

• Assignment Statement:
  name = "Suresh"
  age = 28
  
• Conditional Statement:
  if age >= 18:
      print(f"{name} is eligible to vote.")
  else:
      print(f"{name} is not eligible to vote.")
  
• Loop Statement:
  names = ["Sujatha", "Kavitha", "Sathish"]
  for name in names:
      print(f"Hello, {name}!")
  
• Function Definition Statement:
  def greet_person(name):
      print(f"Good morning, {name}!")
  
  greet_person("Ramesh")
  

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6. Best Practices

• Use meaningful variable names to make statements clear and readable.
• Keep lines short and avoid overly complex statements.
• Use comments to explain the purpose of complex statements.