In Python, control flow means controlling which part of the code runs depending on certain conditions.

Think of your code as a movie — control flow is the director, deciding which scene comes next!

🎬 The if Statement¶

The if statement checks whether a condition is True. If it is, Python executes the code under it.

age = 20

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

Output:

You are an adult!

If the condition is False, the code inside if will be skipped.

🧠 if-else — The Choice Maker¶

Sometimes you want either this or that — not both.

marks = 45

if marks >= 50:
    print("You passed!")
else:
    print("You failed. Study harder next time!")

Output:

You failed. Study harder next time!

😅 Python doesn’t judge, it just executes.

🪜 elif — Multiple Conditions¶

When you have several conditions, use elif (short for “else if”).

temperature = 30

if temperature > 35:
    print("It's too hot! Stay indoors.")
elif temperature > 25:
    print("Nice and warm!")
elif temperature > 15:
    print("Pleasant weather!")
else:
    print("Brr... It's cold!")

🧩 Nested Conditions¶

You can also put an if inside another if — like layers of a samosa 😋

user = "admin"
password = "1234"

if user == "admin":
    if password == "1234":
        print("Access granted!")
    else:
        print("Wrong password!")
else:
    print("Unknown user!")

🔁 Loops — When You Want Repetition¶

Loops let your code repeat itself — like that one song you keep replaying. 🎵

🧮 Looping Through Lists¶

fruits = ["apple", "banana", "cherry"]

for f in fruits:
    print("I like", f)

Output:

I like apple
I like banana
I like cherry

🍌 Notice how Python loops through each fruit without peeling errors!

🌀 for Loop¶

Used when you know how many times to repeat something.

for i in range(5):
    print("Hello!", i)

Output:

Hello! 0
Hello! 1
Hello! 2
Hello! 3
Hello! 4

The range(5) means numbers from 0 to 4 (5 is excluded).

🔄 while Loop¶

Use a while loop when you don’t know how many times to repeat — it keeps looping as long as a condition is true.

count = 1
while count <= 3:
    print("Attempt", count)
    count += 1

Output:

Attempt 1
Attempt 2
Attempt 3

Be careful! If you forget to update count, this loop will never stop. And your CPU will start sweating 💦

⚙️ else with Loops¶

Python allows an else block with loops — it runs only if the loop wasn’t stopped by break.

for i in range(3):
    print("Running:", i)
else:
    print("Loop completed successfully!")

Output:

Running: 0
Running: 1
Running: 2
Loop completed successfully!

If you break out early, the else part won’t run.

Loop Modifiers¶

🛑 break — The Leaver¶

“I’m done. I’m leaving this meeting (loop) right now!”

When Python hits break, it stops the loop completely and exits.

for i in range(5):
    if i == 3:
        break
    print("Number:", i)
print("Loop ended!")

Output:

Number: 0
Number: 1
Number: 2
Loop ended!

As soon as i == 3, Python breaks out — no more looping.

⏭️ continue — The Skipper¶

“I’m still in the meeting, but I’ll skip this boring part.”

continue skips the current iteration and moves to the next one.

for i in range(5):
    if i == 3:
        continue
    print("Number:", i)

Output:

Number: 0
Number: 1
Number: 2
Number: 4

Python skips printing when i == 3, but keeps looping afterward.

😶 pass — The Silent One¶

“I’m here… but I don’t have anything to say yet.”

pass does nothing. It’s a placeholder — useful when you haven’t written code yet, but Python still expects something inside.

for i in range(5):
    if i == 3:
        pass  # I’ll deal with this later
    print("Number:", i)

Output:

Number: 0
Number: 1
Number: 2
Number: 3
Number: 4

Even though i == 3 triggers pass, Python just ignores it and continues normally.

🎭 In Short:¶

👀 Real-World Analogy¶

Imagine you’re watching a Netflix series:

• break → You stop watching and close the laptop 🎬

• continue → You skip an episode but keep watching the rest ▶️

• pass → You sit there doing nothing… maybe buffering? 😅

💡 Pro Tip: Use pass in empty functions, classes, or loops while designing code:

def future_feature():
    pass  # TODO: Add logic later

🧠 Summary Table¶

😂 A Tiny Comedy Moment¶

Student: “Sir, why do we need loops?”

Professor: “So you don’t have to copy-paste print("Hello") 100 times.”

Student: “But I already did that…”

Professor: “Then congratulations, you are the loop.”

💪 Practice Questions¶

1. Write a program to check if a number is positive, negative, or zero.

2. Write a program that prints all numbers from 1 to 10 using a for loop.

3. Write a program that prints only even numbers from 1 to 20.

4. Write a program that checks if a given year is a leap year.

5. Write a program that keeps asking for a password until the user enters "python".

6. Write a program that counts the number of vowels in a given word.

7. Write a program that prints the multiplication table for a given number.

8. Write a program to sum all numbers from 1 to 100 using a loop.

9. Write a program to find the largest number from a list of 5 numbers entered by the user.

10. Bonus Fun One 🎭: Ask the user’s mood — if "happy", print "Keep smiling!"; if "sad", print "Cheer up, Python believes in you!"; else, print "Processing emotions... try again."