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PseudoCode (Video Version)

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    When we write a program,
    we're figuring out a way to turn
  • 0:03 - 0:06
    the brilliant ideas in our head
    into actual code.
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    Here I want to talk about a technique
    that many programmers use to do that,
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    and it's what we call "pseudocode."
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    Now, "pseudocode" is probably a word
    you never heard before,
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    but basically it's code
    that looks a lot like English
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    or really whatever language
    you like to talk in.
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    Well, okay, that may not make sense,
    so let's talk through an actual example.
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    So let's say that I want to draw
    a nice symmetrical face.
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    So I might start by looking at myself
    in the mirror and maybe sketching it out
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    and seeing, okay, well I have this oval face.
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    I have two eyes,
    and they're about at this level.
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    And this is what
    the center of the face is
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    and now I have an idea for what
    I want my face to look like.
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    So I'll start writing it in pseudocode.
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    So let's see, the first thing
    we'd want to do is draw the face,
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    which is an oval, in the center.
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    Then we'd want to draw the two eyes,
    which are two ovals,
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    about two thirds up the face,
    and one fifth the size of the face.
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    Not exact math there
    just looking at my own face.
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    And then we draw the mouth, which is
    a line going halfway across the face,
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    and maybe one third of the way up.
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    So notice how I write
    my pseudocode as comments
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    by starting each line
    with the two slashes here.
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    That way I can write my pseudocode
    in the program itself
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    and not have to worry about
    getting any syntax errors
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    because the program will ignore comments.
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    Now that I've written this in pseudocode,
    I can spend the time to turn
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    each of these lines of pseudocode
    into actual bits of code
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    Right? So let's see, for the face
    I need an oval in the center.
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    For that I'll use the ellipse function for,
    and I'll, you know, figure out
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    the center of the screen here,
    and figure out an eye size.
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    Okay?
    That looks good.
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    For the eyes once again
    those are ellipses.
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    Everything on my face is an ellipse.
    I'm very round.
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    And it's going to be, let's see,
    we'll do some math here to get the eyes
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    at a nice place, and make them
    about a fifth the size.
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    Okay, that looks good for the first eye.
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    I'll just copy paste, make the next eye.
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    Great!
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    Now I can even leave my pseudocode
    for a friend to implement,
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    and they probably could,
    because they can, you know,
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    I have given this really nice description.
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    So I'm going to do that here,
    because, you know, we're friends, right?
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    So, you might think this is silly.
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    Why are we going through the effort
    to write our program twice?
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    First in human language
    and then in program language.
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    Well, this example was pretty simple,
    but pretty soon you'll be building
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    more complex programs,
    and it may be hard for you to keep
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    the whole program in your head
    before coding it.
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    So what I usually do is write the general
    idea in pseudocode first,
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    and then I'll spend more time on
    the details of each part of that idea,
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    converting each line
    of pseudocode into real code.
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    I think you'll find that once you start
    using pseudocode
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    you'll do it more and more.
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    Try it in your next program and see.
Title:
PseudoCode (Video Version)
Description:

This is just a screen grab of our interactive coding talk-through, prepared to make captioning and translation easier. It is better to watch our talk-throughs here:
https://www.khanacademy.org/cs/programming/

more » « less
Video Language:
English
Duration:
03:27
Tanya Higgins approved English subtitles for PseudoCode (Video Version) Aug 10, 2016, 10:19 PM
Tanya Higgins edited English subtitles for PseudoCode (Video Version) Aug 10, 2016, 10:19 PM
Tanya Higgins edited English subtitles for PseudoCode (Video Version) Aug 10, 2016, 9:53 PM
Tanya Higgins edited English subtitles for PseudoCode (Video Version) Aug 10, 2016, 9:35 PM
Chris De Falco edited English subtitles for PseudoCode (Video Version) Dec 3, 2013, 2:54 AM

English subtitles

Revisions

  • Revision 4 Edited
    Tanya Higgins Aug 10, 2016, 10:19 PM