Mastering Python Control Flow: If, Else, and Loops Explained

Control flow allows Python programs to make decisions and repeat actions. This guide covers conditional statements and loops in Python.

Conditional Statements

If Statement

The if statement allows you to execute code only when a condition is True.

age = 18
if age >= 18:
    print("You are an adult.")

If-Else Statement

Use else to specify what happens when the condition is False.

age = 16
if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

Elif (Else If)

Use elif to check multiple conditions.

score = 75
if score >= 90:
    print("Grade: A")
elif score >= 80:
    print("Grade: B")
elif score >= 70:
    print("Grade: C")
else:
    print("Grade: F")

Loops in Python

Loops help automate repetitive tasks.

For Loop

Use for loops to iterate over sequences like lists or strings.

fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

While Loop

Use while loops to repeat a block of code while a condition is True.

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

Break and Continue

• break exits the loop completely.
• continue skips the current iteration and moves to the next one.

for num in range(1, 6):
    if num == 3:
        break  # Stops the loop when num is 3
    print(num)

for num in range(1, 6):
    if num == 3:
        continue  # Skips 3 and continues
    print(num)

Nested Loops

A loop inside another loop is called a nested loop.

for i in range(3):
    for j in range(2):
        print(f"i: {i}, j: {j}")

Conclusion

Understanding control flow is essential for writing efficient Python programs. Practice using if, else, loops, and flow control statements to strengthen your coding skills.

Quiz Questions

1. What is the purpose of an if statement in Python?
2. How does the elif statement differ from if and else?
3. What is the main difference between a for loop and a while loop?
4. What does the break statement do inside a loop?
5. How can you skip an iteration in a loop without stopping it completely?