🤔 Introduction

Making Decisions

Without decisions, a program is just a boring list of commands that always does the exact same thing. By teaching Python to make choices using if and else, your code becomes smart. It can react to different situations!

Every day you make choices. "If it's raining, I'll take an umbrella. Else, I won't." Python does the exact same thing, but it never forgets its umbrella. ☔

⚖️ True or False

Comparing Things

Before Python can make a decision, it needs to ask a question. In Python, questions are called conditionsA condition is a statement that is either True or False. Python uses them to decide what to do.. A condition is always either True or False.

Here are the tools Python uses to compare things:

==

Is equal to

Notice the double equals! Single = is for variables, == is for comparing.

5 == 5    # True
5 == 6    # False

!=

Is NOT equal to

The exclamation mark means "not".

5 != 6    # True
"hi" != "hi" # False

< and >

Less than / Greater than

Standard math symbols.

10 > 5    # True
2 < 1     # False

<= and >=

Less/Greater or Equal

Includes the number itself.

5 >= 5    # True
10 <= 9   # False

🔀 If and Else

Taking Action

Now that we can ask questions, let's use the if and else statements to actually do something.

decisions.py
age = 20

if age >= 18:
    print("You can buy a car!")
else:
    print("Sorry, you need to walk.")if age >= 18:Python checks: is 20 greater than or equal to 18? Yes (True). Also, don't forget the colon : at the end!
    print(...)Notice the space at the start? That's an indent. It tells Python that this code belongs to the "if".
else:If the condition above was False, Python would jump here. (Also needs a colon!)

⚠️ The Importance of Indentation (Spaces)

In many languages, you use curly brackets {} to group code. Python uses spaces (indentation) instead. If you forget to indent the code inside an if, Python will throw an IndentationError. Python is very neat and expects you to be neat too!

🚦 Elif (Else If)

Multiple Choices

What if there are more than two options? Like grades: A, B, C, or F? We use elif (which stands for "else if"). You can have as many elif blocks as you want.

grades.py

          score = 85

if score >= 90:
    print("Grade: A. Sarpanch is proud.")
elif score >= 80:
    print("Grade: B. Not bad!")
elif score >= 70:
    print("Grade: C. Need to study more.")
else:
    print("Grade: F. Oh dear.")
        

Note: Python checks conditions from top to bottom. As soon as it finds one that is True, it runs that code and skips all the rest.

💡 Real-Life Analogy

Think of if/elif/else like standing at a crossroads with signposts.

if: Is this the right path? If yes, go down it.
elif: If not, what about this other path? If yes, take it.
else: If none of the paths were right, take the default path (usually the one home).

🖼️ Diagram

The Pizza Flowchart

An if statement checks a condition. If it's True, it takes one path. If False, it takes the else path.

😂 Sarpanch's Corner

The Food Order

Panel 1

"I made a smart Python script to order food!"

if hungry:
  order_food()

Panel 2

"Wait, I accidentally set hungry = False... what happens now?"

Panel 3

The script finishes without doing anything.

"Oh no... I forgot the else. Now I'm starving!"

🚀 Try It Yourself

Making Decisions

Change the temperature variable and see how Python's decision changes.

💡 Challenges:

Change the temperature to 15. What prints?
Change it to 35. What prints?
Add a new elif condition for when it's exactly 25.

✅ Summary

Decisions — Done! 🚦

Conditions are questions that evaluate to True or False.
Use == to check if things are equal, and != for not equal.
if statements execute code only if the condition is True.
elif lets you check another condition if the first one was False.
else provides a catch-all if absolutely none of the conditions were True.
Indentation (spaces) tells Python which code belongs inside the if/else block!

Awesome! Your code is now smart enough to make choices. Next up, we learn how to make Python do things over and over again without getting tired! 🔄