1
00:00:00,790 --> 00:00:03,190
The following content is
provided under a Creative

2
00:00:03,190 --> 00:00:04,730
Commons license.

3
00:00:04,730 --> 00:00:07,030
Your support will help
MIT OpenCourseWare

4
00:00:07,030 --> 00:00:11,390
continue to offer high quality
educational resources for free.

5
00:00:11,390 --> 00:00:13,990
To make a donation or
view additional materials

6
00:00:13,990 --> 00:00:17,880
from hundreds of MIT courses,
visit MIT OpenCourseWare

7
00:00:17,880 --> 00:00:18,850
at ocw.mit.edu.

8
00:00:23,830 --> 00:00:27,880
PROFESSOR: So now we
have this last exercise.

9
00:00:27,880 --> 00:00:30,310
I'm creating a mysum.

10
00:00:30,310 --> 00:00:32,327
I'm going to go through
all of these values

11
00:00:32,327 --> 00:00:34,660
and you guys have already
told me what values these are,

12
00:00:34,660 --> 00:00:39,640
5, 7, 9, not 11.

13
00:00:39,640 --> 00:00:41,440
And I'm going to add to mysum.

14
00:00:41,440 --> 00:00:44,320
So I'm going to keep a running
sum adding all of these values

15
00:00:44,320 --> 00:00:47,090
together.

16
00:00:47,090 --> 00:00:51,010
So the very first time
through the loop, mysum

17
00:00:51,010 --> 00:00:55,410
gets the value of 5.

18
00:00:55,410 --> 00:00:57,480
That's this line here.

19
00:00:57,480 --> 00:01:01,280
The next thing I see inside
this loop is an if statement.

20
00:01:01,280 --> 00:01:03,510
If mysum is equal to 5.

21
00:01:03,510 --> 00:01:06,330
That's true.

22
00:01:06,330 --> 00:01:08,840
So I'm going to go
inside this if statement.

23
00:01:08,840 --> 00:01:10,430
The next thing I see is a break.

24
00:01:13,220 --> 00:01:15,300
If I see this break
am I evaluating--

25
00:01:15,300 --> 00:01:18,180
am I evaluating
this line or not?

26
00:01:18,180 --> 00:01:19,600
No, exactly.

27
00:01:19,600 --> 00:01:23,990
Because whenever Python sees
break, it's going to say,

28
00:01:23,990 --> 00:01:26,510
I'm going to stop right
here, exit out of the loop

29
00:01:26,510 --> 00:01:29,960
that I'm currently in, and
go to the statement that's

30
00:01:29,960 --> 00:01:32,220
immediately right after it.

31
00:01:32,220 --> 00:01:34,820
So what this is going
to print is mysum.

32
00:01:34,820 --> 00:01:37,280
And that's the exercise
we were looking at.

33
00:01:37,280 --> 00:01:39,000
Let's see how the class did.

34
00:01:41,491 --> 00:01:41,990
Pretty good.

35
00:01:45,370 --> 00:01:48,450
Hopefully if you
answered one of these,

36
00:01:48,450 --> 00:01:50,370
the explanation
was-- was all right.

37
00:01:50,370 --> 00:01:54,410
If not, just go back and try to
work through it step by step.