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Welcome to this coding lecture!
In this lecture, I'm going to show you a few examples about Printf.

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OK and let's get started.

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Now I'm going to show you how you can print the types of variables using Printf.

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By the way, you're not limited to variables only.
Printf can also print the type of any value whether it's

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a variable or not.

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First, let me show you an example here.
Then, I'm going to open my code editor for further examples.

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OK, let's declare a few variables with different types:
var speed int

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var heat float64, var off bool, var brand as a string variable.

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Let's print the type of the speed variable using printf like this.

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So to print the type of a value, I'm using "%T" verb here.
It means: "type".

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Let's run it now.
As you can see, it prints int.

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Let's take a look at the declaration of the speed variable above.

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You can see that Go prints its type as int which is correct.

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Right.

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Now let's print the type of the heat variable using printf again like this.

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Let's see how it prints to the console.
It says float64.

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That's right.

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Now let's print the type of the off variable.
It prints bool this time.

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Let's print the type of the brand variable.
Pause the video and think about what it would print.

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Here is the answer.

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It prints string as expected.

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Alright.

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That's all for this example.

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Now let's take a look at more examples in the coding editor.

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Now I'm going to create a few variables using a multiple declaration statement.

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First, I'm going to declare a new variable named planet.

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with a string value like this.

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Let's print it using printf.

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I'm going to type planet.
As you can see, you can type anything inside the formatting text.

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Now I'm going to type a new verb that you didn't see before.
This "%v" verb is like a swiss-army knife

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for Printf.

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It can print any value.

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If you need to remember one thing about Printf, then this is it.
OK, now I'm going to pass the planet variable

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to Printf.

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OK I'm going to run this program.

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As you can see, Printf prints the formatter by replacing the v verb with the planet variable ('s value).

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This is what I mean by saying that the formatter is like a template. Also notice that it didn't

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print a new line.

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It's because I didn't tell it to do so.

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Let me add a new line escape sequence to the formatter text.

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OK, I'm just going to add \n inside here.

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Alright, let's try it again.

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Did you notice it? Compare the last line with the previous one. This time in the last line, it prints

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a new line.

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Right.

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Now let me declare a few more variables.

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Here's the distance variable.

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It will store the distance to the planet Venus.

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On average Venus is

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261 millions of kilometers away from us.

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So let's initialize it.

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261

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Now I'm going to declare another variable named orbital, like this.
Venus orbits around the sun about

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225 days.

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Now, I'm going to declare the last variable: hasLife.
As far as we know there is no life on Venus, right?

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So I will just type false.
OK let me print those variables using printf.

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I'm going to copy this line here, three times, using cmd+shift+d (ctrl+shift+d on Windows).
Now I'm going to change this planet

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words here by using command+d again.

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Alright.

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Now I'm going to type distance here, and I'm going to pass the distance variable to printf here.

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Let me do the same thing for the orbital variable here.

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OK.

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Alright.

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Now I'm going to use two verbs.

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I'm going to print,

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"does Venus have life?"

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False.

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First I'm going to type: does.

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Then I'll put a verb here.

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So I'm going to pass the planet variable able to printf.

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This was for the first verb. It'll be replaced with Venus because the planet variable's value is

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Venus. And, lastly, I'm going to pass the hasLife variable to printf for the second verb, here.

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This verb will be replaced with false because the hasLife variable's value is false.

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As I said previously, you can add as many verbs and values to printf as you want.

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The rule is that there should be only one formatting text and the number of verbs and the number of

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values should match.

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OK let me fix this line a little bit.

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As long as you end it with a comma you can type it like this.

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OK let's try this now.
Planet Venus

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Distance is 261
Orbital is 224

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All right everything looks right.

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Let's get back.
As I said, the number of verbs and the number of values should match.

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Actually, there is an exception to that rule.

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It's called argument indexing.
By using the argument indexing,

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you can refer to the passed values by their position.
Let me show you. I'm just going to type Printf.

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%v is %v away with a newline character.

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Ok now I'm going to pass two variables: planet and distance.

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All right so far so good.

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This is what you've seen so far.

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OK let's run it

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It prints an expected message, of course.

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All right. Now, without changing the arguments, I'm going to change the formatting text like this.

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This is an argument index, and v here is just the usual v verb

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as you know. So it's typed like this.

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A percent sign and an index, then a formatting verb.

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So two hear tell Printf: "Get me the second argument". And, Printf replaces this whole verb with the

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distance variable.

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This is because if you exclude the formatting text, the distance here is the second argument to the printf.

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So it will replace this verb with the distance.

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And similarly, printf will also replace %[1]v here using the planet variable.

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This is because the planet variable's index position is one.

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It is the first argument to the Printf.

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So in Printf, the indexes start at 1.

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All right.

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Let's run this, as you can see,

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now the printf prints the values multiple times.

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Even I've passed two variables.

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OK, just bookmark this.

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Then you can return back to it later whenever you want.

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OK I'm going to finishing here.
So I'm going to continue in the next lecture.

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OK see you, bye bye.