learngo/02-write-your-first-program/questions/02-code-your-first-program-questions.md

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2018-10-13 23:30:21 +03:00
## What does the package keyword do in the following program?
```go
package main
func main() {
}
```
1. func
2. package *CORRECT*
3. fmt.Println
4. import
> 1. This keyword is used to declare a new function.
> 2. That's right! package keyword allows you to define which package a Go file belongs to.
> 3. This is not a keyword. It's the Println function of the fmt package.
> 4. This keyword is used to import a package.
## Which keyword is used to declare a new function?
* func *CORRECT*
* package
* Println
* import
## What is a function?
1. It's like a mini-program. It's a reusable and executable block of code. *CORRECT*
2. It allows Go to execute a program.
3. It allows Go to import a package called function.
4. It prints a message to the console.
> 2. Go looks for package main and func main to do that. A function doesn't do that on its own.
> 3. `import` keyword does that.
> 4. For example: `fmt.Println` does that.
## Do you have to call the main function yourself?
1. Yes, so that, I can execute my program.
2. No, Go calls the main function automatically. *CORRECT*
> 1. No, you don't need to call the main function. Go automatically executes it.
## Do you have to call the other functions yourself?
1. Yes, so that, I can execute that function. *CORRECT*
2. Yes, so that, Go can execute my program.
3. No, Go calls the functions automatically.
> 1. That's right. You need to call a function yourself. Go won't execute it automatically. Go only calls the main function automatically (and some other functions which you didn't learn about yet).
> 2. That's only the job of the `func main`. There's only one `func main`.
> 3. Go doesn't call any function automatically except the main func (and some other functions which you didn't learn about yet). So, except the main func, you need to call the functions yourself.
## What does `package main` do?
```go
package main
func main() {
}
```
* It controls everything
* It allows you to properly exit from a program
* It allows you to create an executable Go program *CORRECT*
## What does `func main` do?
```go
package main
func main() {
}
```
1. It contains a package called main
2. Go starts executing your program by using the code inside func main *CORRECT*
3. It prints a message to the console
> 1. main function doesn't contain a package.
> 2. That's right. Go automatically calls the main function to execute your program.
> 3. It doesn't print anything at least directly.
## What does `import "fmt"` do?
```go
package main
import "fmt"
func main() {
fmt.Println("Hi!")
}
```
1. It prints "fmt" to the console
2. It defines a new package called "fmt"
3. It imports the `fmt` package; so you can use its functionalities *CORRECT*
> 1. `fmt.Println` prints a message not the `import "fmt"`.
> 2. `package` keyword does that, not the `import` keyword.
> 3. Yes. For example, after you import the fmt package you can call its Println function to print a message to the console.
## What this program does?
```go
package main
func main() {
}
```
1. It prints a message to the console
2. It's a correct program but it doesn't print anything *CORRECT*
3. It's an incorrect program
> 1. It doesn't print a message. To do that you can use fmt.Println function.
> 2. Yes, it's a correct program but since it doesn't contain fmt.Println it doesn't print anything.
> 3. It's a correct program. It uses the package keyword and it has a main function. So, this is a valid and an executable Go program.
## What does this program print?
```go
package main
func main() {
fmt.Println(Hi! I want to be a Gopher!)
}
```
* Hi! I want to be a Gopher!
* It doesn't print anything
* This program is incorrect *CORRECT*
> 1. It doesn't pass the message to Println wrapped between double-quotes. It should be like: fmt.Println("Hi! I want to be a Gopher")
> 3. It doesn't import "fmt" package. Also see #1.
## What does this program print?
```go
package main
import "fmt"
func main() {
fmt.Println("Hi there!")
}
```
* Hi there! *CORRECT*
* fmt
* This program is incorrect; it imports the wrong package or there isn't a function called `Println`
> 2. import "fmt" imports the `fmt` package; so you can use its functionalities.
> 3. Actually, this program is correct.