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In this video, we'll see some of the stream formatting options that are available that

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work with any type of data.

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These are very powerful and easy to use.

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They give you the ability to define a field with

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and then display the next data item,

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either left justified or right justified within that field.

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We can also specify the fill character that will be used to fill up

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any unused space.

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By default, there is no field with defined.

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And all output occurs right after the previous output as we've seen already in this course.

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If you do set a field width,

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then the next data item displayed will default to right justified

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within that field width.

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It's important to understand that if you set the field width and justification,

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they are only applied to the next data item placed on the output stream.

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When we set the fill character, that will persist until you change it.

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Again, this all might sound really complicated but it's pretty easy

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and a few examples will show you exactly how it works.

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But first let's look at the defaults.

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Here's an example that uses absolutely no stream manipulators or methods.

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This is the default behavior when you put data on a stream.

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As you can see, we're displaying the floating point number

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1234.5678 and then the string hello.

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The number will display with 6 digits of precision and it will round.

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And then hello is displayed immediately following the number.

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If we modify this program slightly so that it prints the number and the string each on a new line,

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then we get the number displayed as before

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on the left side with no padding up front followed by the string on the next line.

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So far this is what we've seen and it should be pretty clear.

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So now let's set the field width of the next data item placed on the stream using setw.

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In this case, we're using setw with a 10 as a parameter.

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This will create a field width of 10 for the next data item only.

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In this case, that data item is num.

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Notice that num will be displayed right justified

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by default in the field width of 10.

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I'm displaying a ruler of numbers just above the actual display

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so you can see the alignment.

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This ruler isn't displayed by the code.

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It's only there so you can better follow the examples.

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Notice that the last digit in number, the 7 in this case,

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is displayed in position 10.

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That's the rightmost side of the field width we set earlier.

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But now look what happens when we display hello.

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It displays right next to the number starting in column 11.

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That's because the field width and the justification only apply to the next

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data item placed on the stream. In this case, that data item was num.

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So hello has no field width associated with it,

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and it uses just the defaults.

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In this example, we set the field width of each of the 3 data items to 10.

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And remember, when we have a field width, the default justification is right.

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So in this case, num is displayed right justified in a width of 10.

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The first hello is displayed right justified also in a field of 10.

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And the last hello is also displayed right justified in the width of 10.

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And you can see from the display in the ruler exactly what's happening.

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This example shows how the field width only

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applies to the next data item put on the stream.

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In this case, we set a field width of 10,

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and we want left justification for the next data item, which is num,

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and we get what we expect. Num is displayed in a field width of 10,

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and it's left justified.

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Now we want to display hello.

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Notice that hello has no field width associated with it,

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so it will display starting in column 11.

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In this example, we'll set the field widths for all 3 items displayed.

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Num will have a field width of 10, and it will be right justified by default.

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The first hello will have a field width of 10,

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and we're explicitly setting right justification.

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We don't have to do this since it's the default, but we can do it to be very explicit.

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And the second hello will have a field width of 15,

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and it will also be right justified.

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You can see the output is exactly as we expect.

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Num is right justified in a field width of 10.

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The first hello is right justified in a field width of 10.

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And the final hello is right justified in a field width of 15.

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Now let's take a look at the setfill formatter.

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This only works when a data item has a field width associated with it.

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We supply the character that we want to fill any empty space in the given field width.

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Here's a simple example.

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We're setting the fill character to a dash with the setfill manipulator,

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and we're setting the field width to 10.

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This will apply only to num, which is the next data item on the stream.

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So we expect num to be right justified in a field width of 10,

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and the remaining space in that field to be filled in with dashes.

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That's exactly what we see. But what about the hello that we display next.

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We said that setfill was persistent, but we don't see any dashes with that hello.

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That's because that hello doesn't have a field width associated with it.

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So setfill only applies when we've set the field width.

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So let's look at 1 final example. In this case, we're setting the fill character to an asterisk.

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And then setting the field width of num to 10.

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We expect num to be displayed right justified in a field width of 10

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and asterisk to fill in the remaining space.

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And you can see by the output that that's exactly what we get.

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Now we set the fill character to a dash,

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and the field width to 10 for the first hello.

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We expect hello to display right justified in a field width of 10,

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and the blank space filled in with dashes, again, that's exactly what we get.

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Then finally, we set the field width of the last hello to 15.

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We expect hello to display right justified in a field width of 15.

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And since setfill is persistent and the last hello does have a field width,

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we expect that those blank spaces will be filled in with dashes.

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And as you can see, that's what we get.

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So you see it's really not that complicated, and the rules are very consistent.

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Using the formatting manipulators that we've seen in the last few videos,

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we can have a good amount of control over how our output looks.

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Now let's head over to the IDE, and we'll see these stream formatters in live code.

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Okay. So I'm back. I'm back in the IDE. I'm in the section 19 workspace,

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and I'm in the manip_fields project.

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And what we'll do here is we'll play around with the field with the justification and the setfill.

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You'll notice on line 7 here that I've got a function called ruler

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and all that function does is just display a line of numbers,

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and that way we can line up our columns easier when we see them.

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Okay. You don't have to do this, but it just makes it easier to learn exactly what's going on.

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And then I've got these 3 data items here that I'm using.

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I'm using num1, which is an integer and it's 1234.

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I've got num2, which is a double

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1234.5678,

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and just a simple string hello.

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The first thing we'll do is just like we did in the slides, let's just do the defaults.

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So all we're doing is we're putting num1, num2 and hello onto cout.

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And when we run that, you'll see everything just runs up together.

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So let me build and run. And then we see 1234, that's the integer,

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and then 1234.57, rounded 6 significant figures here,

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that's our precision, and then the hello. Everything jumbled up together,

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right. One right after the other, that's exactly what we expect.

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Okay. We can obviously --

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let me comment this code out. We can obviously

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display one on each line. And sure, that'll help us read it a little nicer

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because now we'll see each one each line.

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But remember, the defaults are being applied.

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So we're getting 1234 as the integer,

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1234.57, which is rounding to the 6th

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precision for the digit and hello again.

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Now let's play around with the field widths.

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And here's a simple example. What we're doing is, again, we're displaying the ruler.

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And then we're setting the field width to 10 for the next

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data item that's being put on the stream, which happens to be num in this case right here.

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So num will be displayed in a width of 10.

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And if you recall num is that integer 1234.

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So that will be displayed in the width of 10, and the default is right justified.

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But then when num2 and hello are displayed,

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there is no field width associated with them. That field width

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only associates with the next item.

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So these 2 should print right next to each other and right next to num1.

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So let's take a look.

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And there you go. You can see 1234 right here.

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And let me grab my pencil, and I'll draw in white, I think it'll be easier to see.

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You can see right here the 1234, right there, that's our integer,

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and that's the 10th, right the 10th column.

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So it's being right justified in the 10th column.

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But then after that, we're seeing our double

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and our string, all printed run right next to the other, no formatting applied.

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Now let's do one more example. Actually let's do a few more examples.

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Let's do this one here. And the source code's available to you,

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I encourage you to go in there and play around and change things around. That's really the best way to learn it.

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Okay. So now look what we're doing. We're setting the width

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to 10 for num1 and for num2.

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So now we expect num1 to be right justified in a width of 10,

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num2 to be right justified in the width of 10,

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and then hello with no formatting, just put right on the end of num2.

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So let's run this.

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And here, down at the bottom, you can see that, that's exactly what happens here.

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There's my field width of 10. And there's 1234, right justified in there.

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Here's the other width of 10 right here the next field.

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And you see 1234.57, right justified in there as well.

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And there's my hello.

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I'm going to put a couple of new lines at the end, just so that

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it'll separate that time elapsed message a little bit,

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so it'll be a little bit easier to see what's going on. And there they are. I just had them commented out.

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So I'll uncomment them.

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Okay. So let's take a look at this example now.

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I will uncomment this code.

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And notice what's happening here, I'm setting the field width to 10

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for each one of those items.

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By default, we're going to right justify everything.

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So num1, num2 and hello will each display right justified in a field width of 10.

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And let's give that a run. And there you go. You can see 1234 the integer

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in the field width of 10, 1234.57

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in its own field width of 10.

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And hello, you can see the 0 right there, right. That would be the 30th column,

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the third field width of 10, and it's right justified.

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Comment this out and see what this is doing.

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Now this is doing exactly the same thing except

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we're left justifying each one of these now.

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Remember, we have we want to left justify then we have to say it explicitly,

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right justified is is the default.

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I always like to put in left and right that way whoever's reading my code afterward

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understands exactly what's going on.

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Even though, we know it's the default

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somebody might have forgotten, so it's nice to see that there.

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So here width of 10, left justified num1,

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width of 10 left justified num2, and width of 10, left justified hello.

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So let's give that a run.

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And you'll see the difference between

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this guy right here where they were right justified and now down here where they're left justified.

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So you can see that 1234 is displaying in column 1,

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1234.57 in column 11,

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and hello in column 21,

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just like we expect. Okay. So now let's do a couple with the setfill,

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and I'll comment this out, we'll walk through this in a minute. So notice what I'm doing here, I'm setting

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the fill character to the dash.

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Now this is a persistent setting. This will persist until I change it.

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And what I'm doing here is I'm setting the width to 10

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left justified num1.

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Now num1 was only 4 digits, right.

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So the rest of the space in that field of 10 is going to be

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padded or filled with that dash character.

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And the same thing will happen to these guys.

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Remember, if we don't have a width set, then setfill doesn't apply.

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It only applies when we're setting the field width. So in this case, we expect to see

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all 3 of these guys. Left justified in a field width of 10.

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And all the spaces that are left over,

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all the blank spaces in that field of 10 filled with dashes. So let's take a look.

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And there you can see right down here.

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You can see 1234, and then dashes all the way to the 10th position.

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And then 1234.57 dashes all the way to the 20th position.

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And then hello and dashes all the way to the 30th position.

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Okay. Had we right justified them the dashes would have been on the left.

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It would have filled any empty space in that field width.

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And the last example is

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we're doing now is we're using different setfill characters.

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So we're setting the filled width to 10 for each one of them again,

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and we're left justifying. And in this first example for num,

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I'm using the asterisk as the fill character. For num2,

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I'm using the hash mark or the pound symbol.

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And for hello, I'm using the dash.

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We should see 3 different fill characters filling up all that space.

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Remember, once this statement is done,

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this is the fill character that's set, so that's going to persist

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until I change it otherwise. All right. So let's run this.

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And there you can see that I'm using the asterisks for the first field,

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the pound signs or the hash symbols for the second field

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and the dashes for the final field.

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Okay. So that's it for this video. In the next video,

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we've got a challenge where we're going to put some of this stuff together to display a table.

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Now you get a chance to play with them and put them together and understand how you can use

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your precision, your left, your right, your fixed and so forth all together

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to create a table of tour prices for trips to South America.

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So that's the challenge coming up in the next video.