90 lines
3.2 KiB
Markdown
90 lines
3.2 KiB
Markdown
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## Which one below is correct?
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**NOTE** _There are explanations inside the answers. Even if you know the answer please try to select all of them one by one, so you can read the explanations._
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1. You can run a library package.
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2. In a library package there should be a function named main (func main).
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3. You can compile a library package. *CORRECT*
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4. You have to compile a library package.
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> 1. You can't, but you can import it from other packages.
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> 2. In a library package, you don't have to include a main function. Because, it isn't an executable package. Only in executable packages you need a main func.
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> 4. You don't have to compile it. When you import it, it will automatically be built by the other program or library when it gets compiled or ran.
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## What do you need to export a name?
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1. You need to type it in all capital letters
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2. You need to type its first letter as a capital letter *CORRECT*
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3. You need to put it inside a function scope
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4. You need to create a new file for that name
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> 1. When you do so, it will be exported, that's true, but don't do that; so I assume that this answer is not correct :)
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> 2. That's right. Then the other packages can access it.
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> 3. It should be in a package scope, not function scope.
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> 4. You don't have to do that.
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## How can you use a function from your library from an executable program?
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1. You need to export your library package first; then you can access to its imported names
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2. You need to import your library package first; then you can access to its exported names *CORRECT*
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3. You can access your library package as if it's in your executable program
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4. You can import it just by using its name
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> 1. You can't export packages. All packages are already exported. Unless you put them in a directory called: "internal". But, that's an advanced topic for now.
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> 2. That's right.
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> 3. You can't access to a package from another package without importing it.
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> 4. No, you can't. You need to import it using its full directory path after GOPATH. BTW, in the near future this may change with the Go modules support.
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## In the following program, which names are exported?
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```go
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package wizard
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import "fmt"
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func doMagic() {
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fmt.Println("enchanted!")
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}
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func Fireball() {
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fmt.Println("fireball!!!")
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}
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```
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1. fmt
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2. doMagic
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3. Fireball *CORRECT*
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4. Println
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> 1. That's just an imported package name.
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> 2. It starts with a lowercase letter; so, it's not exported.
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> 3. That's right. It starts with a capital letter.
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> 4. This isn't your function. It's already been exported in the fmt package. But, it isn't exported here.
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## In the following program, which names are exported?
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```go
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package wizard
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import "fmt"
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var one string
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var Two string
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var greenTrees string
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func doMagic() {
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fmt.Println("enchanted!")
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}
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func Fireball() {
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fmt.Println("fireball!!!")
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}
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```
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1. doMagic and Fireball
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2. Fireball and Two *CORRECT*
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3. Fireball, greenTrees and Two
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4. Fireball, greenTrees, one and Two
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> 1. doMagic starts with a lowercase letter; so, it's not exported.
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> 2. That's right. Fireball and Two, they both start with a capital letter.
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> 3. greenTrees starts with a lowercase letter; so, it's not exported.
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> 4. one and greenTrees do not start with capital letters; so, they're not exported.
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