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

Which keyword below defines a new package for the following program?

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.

Why package main is used in the following program?

package main

func main() {
}

• It creates a library package
• It allows us to properly exit from this program
• It creates an executable Go program CORRECT

Why func main is used in the following program?

package main

func main() {
}

1. It defines a package called main
2. It allows Go to start executing this program by using the code inside func main CORRECT
3. It prints a message to the console

1: main function doesn't create 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.

Why import "fmt" is used in the following program?

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.

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 a function to execute it?

(except the main func)

1. Yes, so that, Go 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 the following program does?

package main

func main() {
}

1. It prints a message to the console
2. It's a correct program and 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?

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?

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.