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Introduction to Python
course content

Course Content

Introduction to Python

Introduction to Python

1. First Acquaintance
The Very First StepsCommentsSome Simple MathMore Challenging MathChallengeBringing It All Together
2. Variables and Types
Storing NumbersNaming RulesUsing VariablesData TypesNumbersChallengeStoring TextString IndexingNegative Indexing and LengthString SlicingChallengeConcatenation
3. Conditional Statements
Boolean Data TypeChallenge: Comparison OperatorsCombining ConditionsChallenge: Logical OperatorsMembership Operators and Types ComparisonSimple if/else ExpressionsChallenge: Grocery StoreChallenge: Odd and Evenif/elif/else ExpressionsChallenge: Grocery Store ExtendedChallenge: Positive, Negative or Zero
4. Other Data Types
What Is a List?List MethodsChallengeNested ListsChallengeWhat Is a Tuple?Tuple MethodsChallengeNested TuplesChallengeWhat Is a Dictionary?ChallengeDictionary MethodsChallenge
5. Loops
while LoopChallengefor LoopChallengeRangeChallengeIterating Over IndexesNested Loops
6. Functions
Built-in FunctionsChallengeDefining Your First FunctionChallengeif/else Statements in FunctionsChallengeFunctions With No ReturnChallengeModifying FunctionsChallengeLambda FunctionsChallenge

bookif/elif/else Expressions

In our last example, you might've picked up on the fact that we didn't account for when the revenue is exactly $2000. In such a scenario, we're neither at a loss nor making a profit. So, we should tweak our code to handle such nuances.

To check a subsequent condition after your initial check, use elif. The structure goes like this:

The code following the final else will run only if none of the previous conditions are met.

Recall our previous example about string length. Let's adjust it. Now, we'll label a string as 'large' if it contains more than 20 characters, 'medium' if it has more than 10 (but certainly no more than 20), and 'small' for anything less.


              
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# Assign some medium string
test = "medium string"

# Conditional statements
if len(test) > 20:
    print("String: '", test, "' is large")
elif len(test) > 10:
    print("String: '", test, "' is medium")
else:
    print("String: '", test, "' is small")
    
# One more checking
test = "small"

# Conditional statement
if len(test) > 20:
    print("String: '", test, "' is large")
elif len(test) > 10:
    print("String: '", test, "' is medium")
else:
    print("String: '", test, "' is small")
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Note

You can stack multiple elif blocks as required. However, it's good to note that overusing elif blocks isn't the most efficient way to structure your code.

Below, you're presented with an `if`/`elif`/`else` block. Given the values, what output would you expect if `b = 150` and if `b = 25`?

Below, you're presented with an if/elif/else block. Given the values, what output would you expect if b = 150 and if b = 25?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

Section 3. Chapter 9
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