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OK, let's just looping.

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So what we're going to do is a little example is we're going to have a program that can draw lines and

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they can draw lines either horizontally, vertically or diagonally.

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And the way we want to do this, and that's just demonstrating in code is a vertical line would look

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something like this.

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So it's just a series of characters going down the screen while the horizontal line would look something

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like this.

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So a series of characters coming across the screen and then a diagonal line would look like this one

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and down.

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Over one.

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Down, you know, over.

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Two spaces.

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And then over three spaces and so on to draw a diagonal line, so we have our three choices and we can

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say how long we want the line to be within reason.

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So we want to do is to first of all, it's like our Frys example.

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We're going to ask, how many do you want a vertical and horizontal line or diagonal and then how many

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how long do you want it to be in length being the number of characters?

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So how do we do that?

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Let's start with a prompt and an answer.

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We'll say let trade equals prompt.

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What type of line and what do we do with the Fry's example and say, let's see each

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horizontal, the vertical, the diagonal.

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So we're going to prompt for that and then we will also prompt for how long you want it to be.

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What does the tribute to LVM equals prompt?

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How long do you want to our line and we won't bother you right now.

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I could type in one million and that would be a little annoying.

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But we won't bother to check for it now.

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And then we'll say, OK, depending on whether it's HVAD, we're going to do something a little bit

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different.

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So let's say let's do a switch like we did or say switch on the type that to upper.

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And then we'll say Case

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H, we're going to do something.

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But we're going to end it with a break case study and we're going to do something with a break case.

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The we're going to do something.

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We're going it with a break.

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Default.

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And just to clarify, we use the prompt to get information from the user, but we're going to still

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really use council dialogue in this program to send information back out.

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So we'll say, counsel, that if I can use a consultant error, I'm not really sure what kind of big

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difference it makes, but we'll say cancel that error and we will say

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00:04:06,210 --> 00:04:11,970
you did not pick a valid line type.

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All right, so we our choices.

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So for right now, let's just see if it works.

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And so we'll just do some consider logs,

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horizontal line.

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And so this could be a vertical line

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and this was going to be a diagonal line.

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All right, let's run this.

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And we need to open up the death tolls, so we'll run a world with that line will say H how long you

50
00:05:07,410 --> 00:05:11,420
want to be 12 horizontal line.

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00:05:11,770 --> 00:05:13,330
OK, looks like it's working.

52
00:05:13,730 --> 00:05:15,640
We can check the other possibilities.

53
00:05:16,240 --> 00:05:19,630
So let's do our horizontal line to start with.

54
00:05:19,930 --> 00:05:24,880
And what we do is use a for loop and we want it to be this length.

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Now, one thing, when we enter this prompt, we're going to get a string.

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And so the string might be the string 23.

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We have to convert it to a number.

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So let's convert it to a number before we get any further down here and say let let's call this Elián

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00:05:42,940 --> 00:05:49,270
String and we'll said that we're not going to change it.

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So let's make it a token one equals.

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And then we can say we use a method on no, we can say no that pass it.

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And what that does is says send a string and we'll give you a number back.

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And I'm not sure right offhand what it does if you send us something that's not a number.

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00:06:16,030 --> 00:06:21,120
But for right now, we'll pretend like we're always going to set a number of songs and strength.

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And if you go back to one of the first examples, the type of loan string would be string and then the

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type of Elian would be no.

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All right.

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So we want to do in here then.

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It's a horizontal line.

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So let's say for what I and traditionally people use I in for loops.

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I'm not sure why maybe for index or something like that.

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00:06:50,680 --> 00:06:58,890
So for I equals zero and we want to do it the length times.

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00:06:59,110 --> 00:07:04,030
So we'll say I less than Leon I was plus.

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00:07:09,420 --> 00:07:16,890
OK, and then also want to do is to we can't say cos of that log and then do it multiple times because

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every time you consider a log it goes down to the next line.

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00:07:19,860 --> 00:07:27,390
So we're going to need to do is, is build this result will build a string and then I'll put it in the

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end.

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00:07:29,070 --> 00:07:32,670
So we'll say let.

79
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Blind string equals an empty string.

80
00:07:42,130 --> 00:07:52,720
So then we will say a line string, and if you recall, you can use the carbonation operator, which

81
00:07:52,720 --> 00:07:57,900
is a plus sign, but you can say plus equals to add on to a string.

82
00:07:59,200 --> 00:08:01,560
So I'll just add plus equals star.

83
00:08:03,550 --> 00:08:09,190
And then at the end it will say carful, that log

84
00:08:12,550 --> 00:08:13,270
line string.

85
00:08:15,910 --> 00:08:16,290
All right.

86
00:08:16,810 --> 00:08:17,800
So let's take a look at this.

87
00:08:21,960 --> 00:08:31,800
We only have the horizontal workings, so let's let's test that and H will say 22 and then we go horizontal

88
00:08:31,800 --> 00:08:32,040
line.

89
00:08:33,930 --> 00:08:39,860
All right, so now we have to do the same thing except with the vertical line.

90
00:08:41,280 --> 00:08:44,040
So let's do more or less the same thing.

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00:08:44,610 --> 00:08:51,240
Now, let me tell you one thing that hasn't really been covered yet, which is that there are nonprofitable

92
00:08:51,240 --> 00:08:55,830
characters are non visible characters, and one of them is called a new line.

93
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In the way that you put it in a new line is it's just added to our line string, just as an example.

94
00:09:04,890 --> 00:09:08,130
Why is our horizontal line, as you put it, in a backslash end?

95
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And that's the new line.

96
00:09:09,600 --> 00:09:13,470
So if I put in a few backslash ends, we'll see if we run this example.

97
00:09:13,470 --> 00:09:20,130
It's going to put us in lines before we get to our I'm messing up with calling things the same thing,

98
00:09:20,130 --> 00:09:23,960
but it's go put in some new lines before we get to the line that we're trying to output.

99
00:09:24,780 --> 00:09:26,190
So also horizontal.

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Twenty two.

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00:09:28,630 --> 00:09:30,950
So you see, it went down a few lines before it got there.

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So with the vertical line, we wanted the exact same thing.

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We want to, but we want to say start new lines, start new lines, start new line.

104
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And that way it's going to go down instead of a cross.

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So here we're essentially going to repeat this, except that we're going to put in the new line.

106
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So why don't we go copy this and we're going to cancel that.

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Load it out.

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And then we're going to start a new line and then each one that adds to it, it's going to go down instead

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of across.

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So let's take a look at that.

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That's the vertical run.

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So say we all say 12 and we go so good that instead of a cross now we can mix this up and do the diagonal

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line.

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It's going to be just a little bit trickier because it's going to have to get down and then it's going

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to have to go across a certain number before we can put it out the star.

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So we need to keep track of how many rows, which is the eye, and do that number.

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So let's copy this for a loop again.

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And back to the beginning, so the follow up is going to cause us to go down, but we also want to go

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across that number.

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So we're going to need a nested for loop.

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So we'll say for Jay and Jay is going to start at zero.

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But each time, you know, we're going to be going down rows.

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So each time is going to go down one over one down to over two, down three over three.

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So we need to put in the very first time we're going to go over zero because it could be on the left

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border and the next time it's going to need to go over one.

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So that corresponds to the value of so we start to set I instead of instead of zero and then we're going

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to need to go that number over.

128
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So we want to go over until J.

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Equals J plus I think or while it's less than that, what J is less than J plus I j plus plus and we'll

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do a little bit of debugging to show how this works.

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00:12:25,630 --> 00:12:31,480
So again, we want to do this, this line string.

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Well, first of all, we're going to add spaces to the line because we're going to go over that amount

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00:12:39,380 --> 00:12:43,780
of outside line string plus equals a space.

134
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And so it's going to push it over until it gets to where it's ready to stop.

135
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And then we're going to add the star and the backslash at.

136
00:12:54,210 --> 00:13:04,530
All right, so let's see what this does may maybe may not work, but we'll try it so diagonal, I will

137
00:13:04,530 --> 00:13:09,360
say five to make it short and did absolutely nothing.

138
00:13:09,520 --> 00:13:12,030
Uh, we need to put in our counsel.

139
00:13:12,030 --> 00:13:13,060
That reminds.

140
00:13:17,220 --> 00:13:20,370
So I see what I'm doing wrong here, which is that this case less than J.

141
00:13:20,370 --> 00:13:24,000
Plus I well, J is going to keep going up, so J.

142
00:13:24,000 --> 00:13:25,410
Plus is going to keep going up.

143
00:13:25,410 --> 00:13:26,430
So it's never going to get there.

144
00:13:27,450 --> 00:13:33,990
So it's actually I times to I believe so.

145
00:13:34,010 --> 00:13:34,590
Let's try that.

146
00:13:35,680 --> 00:13:42,060
OK, let's run this diagonal five.

147
00:13:43,950 --> 00:13:47,840
I was told that a vertical line, so the question is why?

148
00:13:48,420 --> 00:13:54,210
So let's introduce debugging and chrome, which can help us discover what's wrong.

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00:13:55,250 --> 00:14:03,890
So what we do is I have my chrome open up here and you can see that there's a tad sources and we have

150
00:14:03,890 --> 00:14:05,140
our source code in here.

151
00:14:06,500 --> 00:14:08,870
And so what we do is find this position.

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00:14:08,870 --> 00:14:13,880
And I'm going to go over here to the line 24 and do a little click here, and that's going to set a

153
00:14:13,880 --> 00:14:14,950
break in the code.

154
00:14:16,070 --> 00:14:16,820
So let's run.

155
00:14:16,820 --> 00:14:17,810
Hello, world again.

156
00:14:17,820 --> 00:14:24,980
It's going to say, do you want diagonal five that's going to get down here and it's going to pause

157
00:14:24,980 --> 00:14:25,910
in the code here.

158
00:14:26,510 --> 00:14:31,430
And I'm going to make this extra big so it you a little bit better.

159
00:14:32,300 --> 00:14:33,730
So this is different windows.

160
00:14:34,340 --> 00:14:36,830
We have what's called call stack, which we don't worry about.

161
00:14:36,830 --> 00:14:38,750
And then there's local variables into that.

162
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Elian is five.

163
00:14:39,740 --> 00:14:41,570
Alien string is string five.

164
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Our line string is a string.

165
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This is undefined, which won't worry about in our type is the.

166
00:14:48,500 --> 00:14:51,800
And you see we have one breakpoint to find this mother things down here too.

167
00:14:52,190 --> 00:14:55,320
But we're really interested in what's going on with these local variables.

168
00:14:56,180 --> 00:15:05,930
Now you can step in here and you see that the step over the next function call is F ten step into and

169
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step out of.

170
00:15:06,690 --> 00:15:10,260
But we're really right now interested in just this next function call.

171
00:15:10,700 --> 00:15:17,060
So if I click this, it's going to step down a line and it's kind of actually working its way across

172
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the floor right now, says checking the condition.

173
00:15:21,800 --> 00:15:23,160
And now it's coming out of the next slide.

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So our eye is zero and you see that it's defining blocks that saying, OK, you got a block, I zero

175
00:15:31,730 --> 00:15:32,630
your local variables.

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00:15:32,630 --> 00:15:34,430
Are this because they're outside of this block.

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So I'm using the F ten to step because it's a little more convenient.

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So then our eye is zero or eight times to zero.

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RJ is also zero.

180
00:15:47,870 --> 00:15:55,210
Right, because it's going to initialize jaja zero and it's going to say while J is less than eight

181
00:15:55,220 --> 00:15:56,120
times two.

182
00:15:57,650 --> 00:16:02,090
So that's not it is what we want because we don't want to go for any spaces.

183
00:16:03,530 --> 00:16:06,670
So it's going to go over and it's not going to go into that loop at all.

184
00:16:06,680 --> 00:16:10,790
It's going to put in the star all right.

185
00:16:11,510 --> 00:16:21,620
Now or is one and it's because said what J equals one and continue while J is less than eight times

186
00:16:21,620 --> 00:16:22,520
two, which is two.

187
00:16:23,860 --> 00:16:30,880
So it should give us one space, oh, you know what, I could see what I did wrong here and use the

188
00:16:30,880 --> 00:16:32,650
double cross instead of a plus equals.

189
00:16:35,240 --> 00:16:37,840
So let's go back and change this and then we'll step through it again.

190
00:16:40,910 --> 00:16:46,820
So six plus equals so safe,

191
00:16:50,420 --> 00:16:56,440
just needed this this resume, script, execution, know, reload,

192
00:16:59,420 --> 00:17:01,330
so we'll do our run Hello world again.

193
00:17:02,020 --> 00:17:08,780
This kind of say diagonal will say five stops down here.

194
00:17:09,530 --> 00:17:12,110
So now we'll step in to it.

195
00:17:12,920 --> 00:17:15,150
See, our eye is zero.

196
00:17:17,150 --> 00:17:19,510
We don't get a J because the first one doesn't get one.

197
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So we're going to output our line string.

198
00:17:22,190 --> 00:17:24,920
We're going to add star backslash into it.

199
00:17:26,090 --> 00:17:34,220
And you can see it's put a little right or left arrow in here, which is just the symbol for a new line.

200
00:17:36,740 --> 00:17:45,860
So we got to star in a new line and then we get back up here, our eye is now going to be one and our

201
00:17:45,860 --> 00:17:52,190
Jay is going to get the value of one and we're going to add a space to it.

202
00:17:53,810 --> 00:18:03,920
So you can see in our line stringers of space and Jay has the value now to and that is no longer less

203
00:18:03,920 --> 00:18:10,760
than three times to, which is also to just kind of exit and add the star new line to it.

204
00:18:11,420 --> 00:18:16,690
So you can see over here now we have our star new line, Space Star, New Line.

205
00:18:17,900 --> 00:18:19,100
So we continue on.

206
00:18:23,480 --> 00:18:32,600
And we had a space, and this time because our eye is three, we can go one more in another space.

207
00:18:36,080 --> 00:18:39,940
And our star, so you see it's adding one more space each time.

208
00:18:46,430 --> 00:18:54,710
So now it's added more spaces and I'm just going to let it go and click over the console and you can

209
00:18:54,710 --> 00:18:56,570
see we to our diagonal line.

210
00:18:57,230 --> 00:19:01,220
The final thing I want to do with this program is a lot to be executed more than once.

211
00:19:02,280 --> 00:19:04,710
And of course, that's perfect for looping.

212
00:19:06,590 --> 00:19:12,440
So in here, we want to start with the concept that clear always and we know we want to do this at least

213
00:19:12,440 --> 00:19:13,000
once.

214
00:19:13,700 --> 00:19:19,310
So we start with the do, we're just going to say do left curly brace.

215
00:19:20,090 --> 00:19:21,230
So we do it once.

216
00:19:22,160 --> 00:19:31,190
And then down here we're going to say a while and we have to put a condition in there and we have to

217
00:19:31,190 --> 00:19:32,840
finish this with a curly brace as well.

218
00:19:33,920 --> 00:19:37,630
Let's do a reformat so we have to have a wall down here.

219
00:19:37,650 --> 00:19:39,270
The wall does end with a semicolon.

220
00:19:39,980 --> 00:19:41,080
So what's the while?

221
00:19:41,120 --> 00:19:43,130
Well, the wall is we're just going to prompt the user.

222
00:19:44,000 --> 00:19:48,180
We're going to say, let me see.

223
00:19:48,200 --> 00:19:50,300
Twenty four continue equals

224
00:19:52,980 --> 00:19:53,870
confirm

225
00:19:57,020 --> 00:20:00,830
draw another line question mark

226
00:20:03,380 --> 00:20:06,100
and got this one line to load.

227
00:20:06,110 --> 00:20:08,870
Can't be between the wall and the curly brace.

228
00:20:13,230 --> 00:20:19,530
And we're going to have a problem of continuing here because of scoping our continue will not be in

229
00:20:19,530 --> 00:20:22,080
scope, so we're going to find it outside of the loop.

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So I'm going to go up here outside the loop and I'm going to say let's continue equals false.

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And we'll put this in here, and so this is just going to allow us to keep drawing lines while they

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confirm that they want to do it.

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So let's go back to our program run hello world with Llamosa Horizontal or say 55 and draws our line

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55.

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Draw another line.

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Sure.

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Still vertical and we'll say 22 on the line.

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OK, and in this case, say diagonal.

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And I'm going to go back to our source and end this breakpoints.

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So I'm just going to.

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Right.

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Click on it and say remove all breakpoints.

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And back to the council.

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How long do you want your line was, say, 22 as well and just cross our diagonal line, 22 line.

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OK, well, that's our introduction to looping and how to do things multiple times, whether it's with

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a for loop a while loop or do while loop.