Learn Python Control Flow: Conditional Statements and Loops - Textnotes

Learn Python Control Flow: Conditional Statements and Loops

Master Python control flow using if-else conditions, loops, and comprehensions. Learn how to write efficient, readable, and dynamic programs.

Objective:

Learn to control the execution flow of Python programs using conditions, loops, and comprehensions to perform repeated or conditional tasks efficiently.

Topics and Examples:

1. Conditional Statements: if, elif, else

Conditional statements allow Python to execute code only when certain conditions are met.

Example:


age = 18

if age >= 18:
print("You are an adult.")
elif age > 12:
print("You are a teenager.")
else:
print("You are a child.")

2. Loops: for and while

Loops are used to execute a block of code multiple times.

For Loop Example:


# Print numbers from 0 to 4
for i in range(5):
print(i)

While Loop Example:


count = 0
while count < 5:
print(count)
count += 1

3. Loop Control Statements: break, continue, pass

  1. break – exits the loop immediately
  2. continue – skips the current iteration and moves to the next
  3. pass – does nothing, acts as a placeholder

Example:


for i in range(5):
if i == 2:
continue # Skip the number 2
if i == 4:
break # Exit loop when i is 4
print(i)
# pass example
for i in range(3):
pass # Placeholder for future code

Output:


0
1
3

4. List Comprehensions & Dictionary Comprehensions

Comprehensions allow creating lists or dictionaries in a single line, making code concise and readable.

List Comprehension Example:


# Create a list of squares
squares = [x**2 for x in range(5)]
print(squares) # [0, 1, 4, 9, 16]

Dictionary Comprehension Example:


# Create a dictionary of numbers and their squares
squares_dict = {x: x**2 for x in range(5)}
print(squares_dict) # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

This section covers all Python control flow basics: conditional statements, loops, loop control, and comprehensions, with practical examples to practice and master.