1
00:00:00,560 --> 00:00:01,160
Welcome back.

2
00:00:01,670 --> 00:00:10,310
So up until now, we've learned about integers, floats, strings and boolean values, so let's try

3
00:00:10,310 --> 00:00:11,950
and tie some of those things together.

4
00:00:12,620 --> 00:00:14,740
Let's imagine your Facebook.

5
00:00:15,380 --> 00:00:20,510
How do you think Facebook works underneath the hood when it comes to your profile?

6
00:00:21,600 --> 00:00:29,100
Well, they would have, let's say, a variable called name, and this will have your name.

7
00:00:30,340 --> 00:00:36,880
And then they'll probably have a variable with your age, let's say fifty and not actually 50, but

8
00:00:36,880 --> 00:00:44,430
I'm pretending to be for this case just so I sound wiser and then let's say relationship status.

9
00:00:45,370 --> 00:00:49,390
So, again, we also have relationship status on Facebook.

10
00:00:50,020 --> 00:00:52,600
And for now, let's say single.

11
00:00:53,620 --> 00:01:01,360
So that's my Facebook profile right there now, if we wanted to perhaps change that, let's say my relationship

12
00:01:01,360 --> 00:01:04,990
status all of a sudden goes from single to it's complicated.

13
00:01:05,500 --> 00:01:06,970
Well, that's an easy fix.

14
00:01:07,510 --> 00:01:10,930
We would just do relationship status equals to.

15
00:01:12,720 --> 00:01:20,690
It's complicated, I remember because of the single quote, we'll have to do backslash.

16
00:01:26,060 --> 00:01:26,750
Complicated.

17
00:01:27,740 --> 00:01:30,440
And now if I print my relationship status.

18
00:01:31,830 --> 00:01:37,320
You'll see that it's been updated to it's complicated, I am no longer single, hooray!

19
00:01:38,650 --> 00:01:44,470
But this is pretty simple, let's do something more complicated and this is going to be a fun exercise,

20
00:01:45,220 --> 00:01:50,020
let's create a program that I guess is your age.

21
00:01:51,210 --> 00:01:56,140
Let's use the input method that we've seen before.

22
00:01:56,850 --> 00:01:59,610
Remember, the input method allows us to type something.

23
00:02:01,040 --> 00:02:08,870
In here and receive it as input so we can assign that to a variable, so let's say this variable is

24
00:02:08,870 --> 00:02:17,330
going to be birth year and that's going to equal the input that's going to ask.

25
00:02:18,420 --> 00:02:22,620
When or what year were you?

26
00:02:28,590 --> 00:02:35,730
Now, from here, I want you to pause the video and try to solve this yourself, how can you make it

27
00:02:36,090 --> 00:02:41,550
so that at the end of this program you're going to get asked what year, where you're born, you're

28
00:02:41,550 --> 00:02:47,820
going to type in your year, and then it's going to print out your age is whatever the ages.

29
00:02:48,750 --> 00:02:51,570
So pause the video, try and solve this on your own.

30
00:02:52,200 --> 00:02:54,660
Mind you, there is a bit of a trick in here.

31
00:02:54,660 --> 00:03:00,900
So if he gets stuck, try to Google around and figure out what the issue may be.

32
00:03:01,590 --> 00:03:07,140
Again, part of being a programmer is trying to solve these problems that you don't know the answers

33
00:03:07,140 --> 00:03:07,350
to.

34
00:03:09,460 --> 00:03:11,350
All right, let me show you my solution.

35
00:03:12,540 --> 00:03:16,410
We have our birth year here that we're going to store in a variable.

36
00:03:17,940 --> 00:03:26,160
And now we're going to calculate the age, I'm going to say age equals well, it's going to equal the

37
00:03:26,160 --> 00:03:35,310
current year, let's say twenty nineteen and then twenty nineteen here is going to get subtracted from

38
00:03:35,460 --> 00:03:38,800
whatever the birth year that you entered.

39
00:03:39,660 --> 00:03:41,850
So let's enter that.

40
00:03:43,160 --> 00:03:47,960
And then we're simply going to say, print your age is.

41
00:03:49,060 --> 00:03:54,340
And we want to use an F string here, so I'm going to add an F here.

42
00:03:56,330 --> 00:03:58,010
And then simply say.

43
00:04:02,750 --> 00:04:03,770
If I run this.

44
00:04:05,630 --> 00:04:07,490
I get what year were you born?

45
00:04:08,000 --> 00:04:10,460
I was born in 1986.

46
00:04:12,140 --> 00:04:19,820
Hmm, we get an error, and if you try this yourself, you may have encountered this error, we get

47
00:04:19,820 --> 00:04:25,790
something called a type error and there's lots of errors that you can get in Python.

48
00:04:26,570 --> 00:04:29,960
Again, we have a section on air, so don't stress too much about it.

49
00:04:30,260 --> 00:04:39,260
But if you read here, it says unsupported operand type S four minus Int and string.

50
00:04:40,530 --> 00:04:44,040
Hmmm, let's try and debug this.

51
00:04:44,220 --> 00:04:48,750
It looks like we're using minus on an integer and a string.

52
00:04:49,510 --> 00:04:56,760
So let me print out here the type of birth year.

53
00:04:57,700 --> 00:05:07,420
If I run this and let's enter in nineteen eighty six, I get class string and this is a little gotcha

54
00:05:07,780 --> 00:05:12,970
because what input does is it asks you for an input.

55
00:05:13,150 --> 00:05:21,640
But that input that I wrote one nine eight six, well that actually gets converted to a string and assigned

56
00:05:21,640 --> 00:05:22,600
to birth year.

57
00:05:23,550 --> 00:05:27,660
So what that means is that we're trying to subtract.

58
00:05:28,850 --> 00:05:32,270
A number or a string from a number.

59
00:05:33,510 --> 00:05:35,280
So how do we solve this issue?

60
00:05:36,550 --> 00:05:44,590
Well, you'd have to turn this into an integer, and this is something that we saw previously, what

61
00:05:44,590 --> 00:05:52,180
we need to do is to convert this into an integer with using the INT function.

62
00:05:53,260 --> 00:05:59,140
So let's try that if I remove this and click run.

63
00:06:00,520 --> 00:06:02,110
I'll say nineteen eighty six.

64
00:06:04,170 --> 00:06:07,590
And look at that, your age is 33.

65
00:06:08,810 --> 00:06:13,940
We've created a program that is able to tell your age based on the year that you were born.

66
00:06:14,780 --> 00:06:21,860
Now, this may have been tricky to you, but it teaches an important concept in programming that is

67
00:06:21,890 --> 00:06:29,690
sometimes you storing data into different data types and sometimes you need those different data types

68
00:06:29,690 --> 00:06:31,280
to interact together.

69
00:06:32,260 --> 00:06:38,770
So you'll see a lot of problems where you have to convert a data type and this is a very common one

70
00:06:38,920 --> 00:06:45,010
where you take an input that's a string and then you convert it to something like an integer.

71
00:06:46,100 --> 00:06:53,090
So he can perform a mathematical operation, and that's why if you remember, we gave you a list of

72
00:06:53,090 --> 00:06:58,760
all our data types in Python, the fundamental data types, and all of them were blue because, well,

73
00:06:58,760 --> 00:07:03,290
each one of these are actions are functions that we can use.

74
00:07:04,270 --> 00:07:13,180
For example, I converted the birth year into integer, but I could have also converted this to a float,

75
00:07:13,330 --> 00:07:21,340
for example, and if I run this, it would still work because Python knows that, well, we can use

76
00:07:21,340 --> 00:07:27,380
integers and floats in mathematical operation, but you can see here that it's converted into a float.

77
00:07:27,510 --> 00:07:30,940
Now, if we convert this into a boolean.

78
00:07:31,950 --> 00:07:33,240
And I click run.

79
00:07:36,420 --> 00:07:40,720
Your age is twenty eighteen, that's really confusing, right?

80
00:07:40,920 --> 00:07:48,780
Well, that's because this gets turned into true and underneath the hood, python does something weird

81
00:07:48,780 --> 00:07:57,040
where a true value is converted to one because boolean remember, it's one or zero, true or false.

82
00:07:57,930 --> 00:07:58,350
All right.

83
00:07:58,560 --> 00:08:00,770
Hopefully this didn't confuse you too much.

84
00:08:00,780 --> 00:08:02,980
It's something that will encounter throughout the course.

85
00:08:02,980 --> 00:08:05,400
So don't worry, we'll get more and more practice.

86
00:08:06,090 --> 00:08:11,100
However, I hope you get to practice this a little bit to really understand what's going on, because

87
00:08:11,100 --> 00:08:17,580
although this is a couple of lines of code, the principles that we use here, we're going to use throughout

88
00:08:17,580 --> 00:08:19,170
bigger and bigger code bases.

89
00:08:20,200 --> 00:08:21,680
So I guess I'll see you in the next one.

90
00:08:22,120 --> 00:08:22,480
Bye bye.