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- Okay, so I'm gonna close the code file.

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I'll just clap things down.

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I'm gonna give myself a bit more space

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in my terminal window,

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so we can actually see
things a bit better.

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Cargo run.

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If this is the first time

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that you're running the
application yourself,

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at this point, it'll
probably spend about a minute

10
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downloading dependencies.

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I've already run this application before,

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so it just starts immediately.

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This is the menu.

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I can display all visits.

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Yes. Let's choose option one.

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Press enter and it's already read the data

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from the file into memory
when the application started.

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So when I choose option one,

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it'll just display all the
visits that it read in.

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There we go.

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00:00:53,100 --> 00:00:55,950
Okay, so those are all the visits.

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Start date, end date, and the
place name and description.

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And that was fairly straightforward.

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At the end, it then redisplays the menu.

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That's quite nice.

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So let's say this time or
to calculate the visit days

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within a period of interest.

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What I was anxious about
with this Brexit thing,

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if I book a course in three months' time,

30
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what will be my number of
days at that point in time?

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So I'm okay now, but
if I book these courses

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in like July, August, September,

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by the time it gets to the end of October,

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what's my number gonna look like then?

35
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Am I still less than 90?

36
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So if I choose option two,

37
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it says what reference
date do you want to use?

38
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Like from when do you wanna
start counting backwards?

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Well, today's date here
is the 26th of May.

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So maybe I'll add to that.

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So it's year, year, year,
then month, month, day, day.

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So 2023.

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The month is month five, and
today's date is the 26th.

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I think it's the 25th actually.

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25th.

46
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Oh, so in that case, if you choose today,

47
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it'll only tell you, it
doesn't tell you, you know,

48
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how many days you're on for previous days.

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Who cares what my day count was yesterday

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'cause yesterday's gone.

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So how about if I choose a date?

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I'll do the option
again, option number two

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but I'll choose the end of the year,

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2023, December the 31st.

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So it'll display all the dates
from there back to today.

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And it'll tell me for each
date, what's my day count?

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So like from the 31st of December,

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if you go back 180 days from then,

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how many days was I in Europe?

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And then it'll say from
the day before that,

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the 30th of December, how
many days were you in Europe?

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And it'll do that backwards all the time

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until it gets back to today.

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So if I enter,

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all right, it actually displays
two sets of information.

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When I first wrote the application,

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I realized it would actually be useful

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to see this information
in two different ways.

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If I go back up to the top,

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we have lots of discussions about Brexit

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00:03:30,960 --> 00:03:33,483
and none of them ever
go well, to be honest.

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So I'm scrolling up to
the top of the output.

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So it actually displays
two blocks of information.

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First of all, it says from
whatever date you specified,

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31st of December,

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at that point, if you look
back for the previous 180 days,

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you'll have been away
in that period 67 days.

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00:03:59,970 --> 00:04:02,790
And then it says for the 30th of December,

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if you go back 180 days,
you'll have been away 67 days.

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00:04:07,800 --> 00:04:08,640
But if I scroll down,

81
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let's say I pick out the 3rd
of December, my birthday,

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did I mention that?

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On the 3rd of December,

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if you look back the 180 days before that,

85
00:04:19,620 --> 00:04:22,470
you'd have been away 75 days.

86
00:04:22,470 --> 00:04:25,410
So this information, when I look at it,

87
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it gives me an indicator

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of where it's starting
to get a bit close to 90,

89
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which I'm not allowed to go over.

90
00:04:33,254 --> 00:04:38,254
So a little bit scary actually
here on the, oh, what's that?

91
00:04:39,690 --> 00:04:42,660
On the 4th of November,

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00:04:42,660 --> 00:04:46,476
if you count from there
backwards 180 days,

93
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I would've been away
in Europe for 89 days.

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That's basically almost 90.

95
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I'd only have to have a overstay

96
00:04:53,880 --> 00:04:56,760
by one night because of storm.

97
00:04:56,760 --> 00:04:59,970
And I've only got one day margin,

98
00:04:59,970 --> 00:05:04,920
so I need to be careful booking
courses that will, you know,

99
00:05:04,920 --> 00:05:08,073
around that date or within the
period leading to that date.

100
00:05:09,810 --> 00:05:11,520
If I go back, what's
the current day today?

101
00:05:11,520 --> 00:05:16,440
So we're currently on, well,
let's pick the 1st of October,

102
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1st of August.

103
00:05:18,000 --> 00:05:22,980
On the 1st of August, in
the 180 days previously,

104
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I'll have been away 74 days.

105
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So you get the idea.

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It tells you where the hotspots are.

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It tells me where I need to start being

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a bit more careful about bookings.

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What a sorry state of
affairs this is, Brexit.

110
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I thought the other way would be useful,

111
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would be actually to show the dates,

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not from chronologically backwards,

113
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but in terms of the maximum
number of days I was away.

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So the maximum of days was actually 89.

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And there were several days
because I was away in a period,

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on each of these days, I'll
have been away for 89 days

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in the previous 180.

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So it gives me a feeling
for how close I am

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00:06:03,630 --> 00:06:07,350
to the edge in terms of
my allowance like that.

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So that displays the dates.

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The first output displayed the dates

122
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in reverse chronological order,
and then the second output,

123
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the same data, but this time,

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displayed in reverse number
of days that I've been away.

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So I can keep on top of it.

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There is actually an app I discovered

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that you can get on the
iPhone or on a Galaxy,

128
00:06:29,700 --> 00:06:30,692
on an Android device

129
00:06:30,692 --> 00:06:33,540
that actually counts your
Schengen visits for you.

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00:06:33,540 --> 00:06:36,240
But it was a lot more fun
writing a Rust application.

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Okay, so that's basically the data.

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I can add a visit.

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00:06:40,200 --> 00:06:41,940
I'm not sure if I can
actually, I think I'm full

134
00:06:41,940 --> 00:06:43,230
but I could add a visit potentially.

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That's option number three.

136
00:06:44,700 --> 00:06:47,670
Option number three, I've
gotta enter the start-date

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and the end-date and the description.

138
00:06:49,740 --> 00:06:53,400
So let's say December
looked pretty available.

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00:06:53,400 --> 00:06:56,310
So let's say I go away on the,

140
00:06:56,310 --> 00:07:00,243
it's gonna be year, month,
day format 2023, the 12th.

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00:07:01,500 --> 00:07:04,170
December is usually a very
busy month for training

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because a lot of companies
have a budget for training,

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00:07:07,440 --> 00:07:09,570
which expires at the end of the year

144
00:07:09,570 --> 00:07:12,780
and they have December to
use the budget or lose it.

145
00:07:12,780 --> 00:07:17,310
So let's say I go away
on the 10th of December

146
00:07:17,310 --> 00:07:22,310
and I come back on the 2023-12.

147
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It's usually for a week.

148
00:07:23,520 --> 00:07:25,680
So let's say the 18th of December,

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using one day exclusive.

150
00:07:28,710 --> 00:07:33,710
Visit to Lapland to see Santa.

151
00:07:36,240 --> 00:07:38,670
That was on the list several years ago

152
00:07:38,670 --> 00:07:40,650
when our children were littler.

153
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Didn't actually go though.

154
00:07:41,610 --> 00:07:43,413
A lot of money for one day.

155
00:07:44,610 --> 00:07:47,010
But anyway, I'm going for eight days.

156
00:07:47,010 --> 00:07:50,430
Okay, so that option has now
been added into the list.

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00:07:50,430 --> 00:07:54,660
And what I could do is I
could choose option four

158
00:07:54,660 --> 00:07:59,660
to save that new data back
to my file and then exit.

159
00:07:59,700 --> 00:08:03,270
Or I can choose option five
to exit without saving.

160
00:08:03,270 --> 00:08:04,870
So I'm gonna choose option five.

161
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Like so.

162
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And then the application's finished.

163
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So as you can see, it's quite
a useful application really.

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00:08:16,200 --> 00:08:18,450
It's not the most complicated
thing you'll ever see

165
00:08:18,450 --> 00:08:20,940
but it's complicated enough.

166
00:08:20,940 --> 00:08:23,760
Aspects of it, miscellaneous things,

167
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date handling, string handling,

168
00:08:25,350 --> 00:08:28,650
getting input from the
user, utility stuff.

169
00:08:28,650 --> 00:08:33,270
Obviously, file handling,
displaying menus and looping

170
00:08:33,270 --> 00:08:35,880
and a bit of date handling as well.

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So now that you know how
the application works

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00:08:39,270 --> 00:08:42,690
in terms of the
functionality that it gives,

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what we're gonna do for
the rest of the lesson

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00:08:44,340 --> 00:08:45,420
is dive into the code

175
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and see the details of how
it actually achieves it.