Key Concepts

Review core concepts you need to learn to master this subject

Conditional Control

Control Flow

elif Statement

Handling Exceptions in Python

or Operator

Equal Operator ==

Not Equals Operator !=

Comparison Operators

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Conditional Control

Conditional statements or conditional control structures allow a program to have different behaviors depending on certain conditions being met.

Intuitively, this mimics the way humans make simple decisions and act upon them. For example, reasoning about whether to go outside might look like:

  • Condition: Is it raining outside?
    • If it is raining outside, then bring an umbrella.
    • Otherwise, do not bring an umbrella.

We could keep adding clauses to make our reasoning more sophisticated, such as “If it is sunny, then wear sunscreen”.

Control Flow
Lesson 1 of 2
  1. 1
    Control Flow
    How do computers make decisions? Here are a few examples: * Web surfing: Open the browser, load the text, load the images. * Social media: If the user’s profile is private, hide their posts. Other…
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  2. 2
    Conditional
    If the user’s profile is private, hide their posts. Otherwise, make them visible. Computers can run instructions on their own, leaving us to work on more interesting and creative problems. But c…
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  3. 3
    Loop
    Repeat a sound four times a measure. Computers are good at repetitive tasks: they exactly follow instructions and perform them quickly. But if the programmer has to write the same instructions f…
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  4. 4
    Exception
    Collect shipping and email address. Reject a purchase if either is incorrect. Errors, or exceptions, happen all the time in programming. You can’t escape them. But you can handle them gracefully…
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  5. 5
    Putting It All Together
    Let’s recreate the conditional control structure using JavaScript! (The one about social media posts, remember?) ![Diagram of conditional control structure](https://content.codecademy.com/progra…
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  6. 6
    Review
    Well done! Control flow is a fundamental concept in programming, and learning the basics will serve you wherever your path leads, regardless of language or domain. In review: - Control flow is t…
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