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PROFESSOR ERIC GRIMSON: All
right, I'm going to start
00:00:22
today by talking about, so
what have we been doing?
00:00:26
What have we actually done
over the last few lectures?
00:00:28
And I want to suggest that what
we've done is, we've outlined a
00:00:32
lot of the basic elements
of programming.
00:00:35
A lot of the basic elements
we're going to need
00:00:37
And I want to just highlight it
for you because we're going
00:00:39
to come back and look at it.
00:00:40
So I'm going to suggest
that we've looked at three
00:00:43
different kinds of things.
00:00:45
We've talked about data, we've
talked about operations,
00:00:51
and we've talked about
commands or statements.
00:01:00
Data's what we expect.
00:01:01
It's our way of representing
fundamentally the kinds of
00:01:05
information we want
to move around.
00:01:06
And here, I'm going to suggest
we've seen numbers, we've seen
00:01:11
strings, and I'm going to
add Booleans here as well.
00:01:16
They're a third kind of value
that we saw when we started
00:01:19
talking about conditions.
00:01:21
We saw, associated with that
primitive data, we have ways of
00:01:24
taking data in and creating new
kinds of data out, or new
00:01:27
versions of data out,
so we have operations.
00:01:31
Things like addition and
multiplication, which we saw
00:01:33
not only apply to numbers, but
we can use them on things like
00:01:36
strings and we're going to
come back to them again.
00:01:38
Can't use them on Booleans,
they have a different
00:01:41
They do things
like AND, and OR.
00:01:45
And of course there's a bunch
of other ones in there, I'm not
00:01:47
going to put them all up, but
we're building up a little
00:01:49
collection, if you like,
of those operations.
00:01:52
And then the main thing
we've done is, we've
00:01:53
talked about commands.
00:01:54
So I'm going to suggest we've
seen now four different things.
00:01:57
We've seen assignment, how
to bind a name to a value.
00:02:04
We've seen input and output.
00:02:10
Print for output, for example,
and raw input for input.
00:02:15
We've seen conditionals, or
said another way, branches,
00:02:23
ways of changing the flow of
control through that
00:02:26
sequence of instructions
we're building up.
00:02:28
And the last thing we added
were loop mechanisms.
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