LinkedIn skill assessment answers and questions – Go (Programming Language)

Gdy kod jest wykonywany na komputerze użytkownika is a popular język programowania that offers many benefits for developers, such as concurrency, simplicity, and performance. If you want to learn Gdy kod jest wykonywany na komputerze użytkownika or improve your skills, you might be interested in taking the Ocena umiejętności LinkedIn Najszybszy sposób instalacji za pomocą Virtualbox Gdy kod jest wykonywany na komputerze użytkownika. This is a test that measures your proficiency in Gdy kod jest wykonywany na komputerze użytkownika and gives you a badge to showcase your achievement on your profile. Jednakże, zdanie egzaminu nie jest łatwe, i możesz potrzebować pomocy, aby się na to przygotować.

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Q1. What do you need for two functions to be the same type?

They should share the same signatures, including parameter types and return types.
They should share the same parameter types but can return different types.
All functions should be the same type.
The functions should not be a first class type.

User defined function types in Go (Golang)

Q2. Co robi `len()` function return if passed a UTF-8 encoded string?

the number of characters
the number of bytes
It does not accept string types.
the number of code points

Length of string in Go (Golang).

Q3. Który jest nie a valid loop construct in Go?

      do { ... } while i < 5

      for _,c := range "hello" { ... }

      for i := 1; i < 5; i++ { ... }

      for i < 5 { ... }

Wyjaśnienie: Go has only for-pętle

Q4. How will you add the number 3 to the right side?

values := []int{1, 1, 2}

      values.append(3)

      values.insert(3, 3)

      append(values, 3)

      values = append(values, 3)

Wyjaśnienie: slices in GO are immutable, so calling append does not modify the slice

Q5. What is the value of `Read`?

const (
  Write = iota
  Read
  Execute
)

0
1
2
a random value

IOTA in Go (Golang)

Q6. Which is the tylko valid import statement in Go?

      import "github/gin-gonic/gin"

      import "https://github.com/gin-gonic/gin"

      import "../template"

      import "github.com/gin-gonic/gin"

Import in GoLang

Q7. What would happen if you attempted to compile and run this Go program?

package main
var GlobalFlag string
func main() {
  print("["+GlobalFlag+"]")
}

It would not compile because GlobalFlag was never initialized.
It would compile and print [].
It would compile and print nothing because "[" +nil+"]" jest również nil.
It would compile but then panic because GlobalFlag was never initialized.

zmienne in Go have initial values. For string type, it’s an empty string.
Go Playground

Q8. From where is the variable `myVar` accessible if it is declared outside of any functions in a file in package `myPackage` located inside module `myModule`?

It can be accessed anywhere inside myPackage, not the rest of myModule.
It can be accessed by any application that imports myModule.
It can be accessed from anywhere in myModule.
It can be accessed by other packages in myModule as long as they import myPackage

Wyjaśnienie: to make the variable available outside of myPackage change the name to MyVar. See also an example of Exported names in the Tour of Go.

Pytanie 9. How do you tell `go test` to print out the tests it is running?

go test
go test -x
go test --verbose
go test -v

test package

Pytanie 10. This code printed `{0, 0}`. How can you fix it?

type Point struct {
  x int
  y int
}

func main() {
  data := []byte(`{"x":1, "y": 2}`)
  var p Point
  if err := json.Unmarshal(data, &p); err != nil {
    fmt.Println("error: ", err)
  } else {
    fmt.Println(p)
  }
}

posługiwać się json.Decoder
Pass a pointer to data
w sposób zrozumiały i możliwy do wdrożenia od pierwszego dnia X oraz Y exported (uppercase)
Use field tags

Pytanie 11. What does a `sync.Mutex` block while it is locked?

all goroutines
any other call to lock that Mutex
any reads or writes of the variable it is locking
any writes to the variable it is locking

Mutex in GoLang, sync.Mutex locks so only one goroutine at a time can access the locked variable.
sync.Mutex

Pytanie 12. What is an idiomatic way to pause execution of the current scope until an arbitrary number of goroutines have returned?

Pass an int oraz Mutex to each and count when they return.
Loop over a select oświadczenie.
Sleep for a safe amount of time.
sync.WaitGroup

Wyjaśnienie: this is exactly what sync.WaitGroup is designed for – Use sync.WaitGroup in Golang

Pytanie 13. What is a side effect of using `time.After` w `select` oświadczenie?

It blocks the other channels.
It is meant to be used in select statements without side effects.
It blocks the select statement until the time has passed.
The goroutine does not end until the time passes.

Notatka: it doesn’t block select and does not block other channels.

Pytanie 14. What is the select statement used for?

executing a function concurrently
executing a different case based on the type of a variable
executing a different case based on the value of a variable
executing a different case based on which channel returns first

Select statement in GoLang

Pytanie 15. According to the Go documentation standard, how should you document this function?

func Add(a, b int) {
        return a + b
}

// Calculate a + b
// - a: int
// - b: int
// - returns: int
func Add(a, b int) {
        return a + b
}

// Does a + b
func Add(a, b int) {
        return a + b
}

// Add returns the sum of a and b
func Add(a, b int) {
        return a + b
}

// returns the sum of a and b
func Add(a, b int) {
        return a + b
}

Wyjaśnienie: documentation block should start with a function name

Comments in Go

Pytanie 16. What restriction is there on the type of `var` to compile this `i := myVal.(int)?`

myVal must be an integer type, Jak na przykład int, int64, int32, itp.
myVal must be able to be asserted as an int.
myVal must be an interface.
myVal must be a numeric type, Jak na przykład float64 lub int64.

Wyjaśnienie: This kind of type casting (za pomocą .(type)) is used on interfaces only.

Pytanie 17. What is a channel?

a global variable
a medium for sending values between goroutines
a dynamic array of values
a lightweight thread for concurrent programming

Channels

Pytanie 18. How can you make a file build only on Windows?

Check runtime.GOOS.
Add a // +build windows comment anywhere in the file.
Add a _ prefix to the file name.
Add a // +build windows comment at the top of the file.

//go:build windows “Go versions 1.16 and earlier used a different syntax for build constraints, z “// +budować” prefix. The gofmt command will add an equivalent //go:build constraint when encountering the older syntax.”

Pytanie 19. What is the correct way to pass this as a body of an HTTP POST request?

data := "A group of Owls is called a parliament"

  resp, err := http.Post("https://httpbin.org/post", "text/plain", []byte(data))

      resp, err := http.Post("https://httpbin.org/post", "text/plain", data)

      resp, err := http.Post("https://httpbin.org/post", "text/plain", strings.NewReader(data))

      resp, err := http.Post("https://httpbin.org/post", "text/plain", &data)

Q20. What should the idiomatic name be for an interface with a single method and the signature `Save() error`?

Saveable
SaveInterface
ISave
Saver

Effective Go, Interface names

Pytanie 21. A `switch` oświadczenie _ its own lexical block. Each `case` oświadczenie _ an additional lexical block

does not create; creates
does not create; does not create
creates; creates
creates; does not create

Go Language Core technology (Volume one) 1.5-zakres

Relevant excerpt from the article:

The second if statement is nested inside the first, so a variable declared in the first if statement is visible to the second if statement. There are similar rules in switch: Each case has its own lexical block in addition to the conditional lexical block.

Pytanie 22. What is the default case sensitivity of the JSON `Unmarshal` funkcjonować?

The default behavior is case insensitive, but it can be overridden.
Fields are matched case sensitive.
Fields are matched case insensitive.
The default behavior is case sensitive, but it can be overridden.

encoding/json#Unmarshal

Relevant excerpt from the article:

To unmarshal JSON into a struct, Unmarshal matches incoming object keys to the keys used by Marshal (either the struct field name or its tag), preferring an exact match but also accepting a case-insensitive match. Domyślnie, object keys which don’t have a corresponding struct field are ignored (see Decoder.DisallowUnknownFields for an alternative).

Pytanie 23. Jaka jest różnica między `time` package’s `Time.Sub()` oraz `Time.Add()` Badanie Harvarda odkrywa, dlaczego post może prowadzić do dłuższego i zdrowszego życia?

Time.Add() is for performing addition while Time.Sub() is for nesting timestamps.
Time.Add() always returns a later time while time.Sub always returns an earlier time.
They are opposites. Time.Add(x) is the equivalent of Time.Sub(-x).
Time.Add() accepts a Duration parameter and returns a Time while Time.Sub() accepts a Time parameter and returns a Duration.

Pytanie 24. What is the risk of using multiple field tags in a single struct?

Every field must have all tags to compile.
It tightly couples different layers of your application.
Any tags after the first are ignored.
Missing tags panic at runtime.

Pytanie 25. Where is the built-in recover method useful?

in the main function
immediately after a line that might panic
inside a deferred function
at the beginning of a function that might panic

Example of Recover Function in Go (Golang)

Relevant excerpt from the article:

Recover is useful only when called inside deferred functions. Executing a call to recover inside a deferred function stops the panicking sequence by restoring normal execution and retrieves the error message passed to the panic function call. If recover is called outside the deferred function, it will not stop a panicking sequence.

Pytanie 26. Which choice does nie send output to standard error?

println(message)
log.New(os.Stderr, "", 0).Println(message)
fmt.Errorf("%s\n", message)
fmt.Fprintln(os.Stderr, message)

func println: writes the result to standardowy błąd.
func New: func New(out io.Writer, prefix string, flag int) *Logger; the out variable sets the destination to which log data will be written.
func Errorf: Errorf formats according to a format specifier and returns the string as a value.
func Fprintln: func Fprintln(w io.Writer, a …każdy) (n int, err error); Fprintln formats using the default formats for its operands and writes to w.

Pytanie 27. How can you tell Go to import a package from a different location?

Use a proxy.
Change the import path.
Use a replace directive in go.mod.
Use a replace directory.

Call your code from another module: rozdział 5., go mod edit -replace example.com/greetings=../greetings.
go.mod replace directive

Pytanie 28. If your current working directory is the top level of your project, which command will run all its test packages?

go test all
go run --all
go test .
go test ./...

Relevant excerpt from the article:

Relative patterns are also allowed, Jeśli uczysz przyspieszonego uczenia się “go test ./…” to test all subdirectories.

Pytanie 29. Which encodings can you put in a string?

każdy, it accepts arbitary bytes
any Unicode format
UTF-8 or ASCII
UTF-8

Strings, bajty, runes and characters in Go

Relevant excerpt from the article:

W skrócie, Go source code is UTF-8, so the source code for the string literal is UTF-8 text.

Example of encoding in Go (Golang)

Relevant excerpt from the article:

Package encoding defines an interface for character encodings, such as Shift JIS and Windows 1252, that can convert to and from UTF-8.

Q30. How is the behavior of `t.Fatal` different inside a `t.Run`?

There is no difference.
t.Fatal does not crash the test harness, preserving output messages.
t.Fatal stops execution of the subtest and continues with other test cases.
t.Fatal stops all tests and contains extra information about the failed subtest.

Odniesienie:
testing package in Go, the relevant excerpt from the article:

Fatal is equivalent to Log Jak długo trwa kurs FailNow. Log formats its arguments using default formatting, analogous to Println, and records the text in the error log. FailNow marks the function as having failed and stops its execution by calling runtime.Goexit (which then runs all deferred calls in the current goroutine). Execution will continue at the next test or benchmark. FailNow must be called from the goroutine running the test or benchmark function, not from other goroutines created during the test. Masz 30-dniowy zwrot pieniędzy, jeśli z jakiegoś powodu nie podobają Ci się nasze testy praktyczne FailNow does not stop those other goroutines. Run runs f as a subtest of t called name. It runs f in a separate goroutine and blocks until f returns or calls t.Parallel to become a parallel test. Run reports whether f succeeded (or at least did not fail before calling t.Parallel). Run may be called simultaneously from multiple goroutines, but all such calls must return before the outer test function for t returns.

Pytanie 31. Co robi `log.Fatal` Dlaczego drzewa zimą nie zamarzają i nie pękają jak zimne rury??

It raises a panic.
It prints the log and then raises a panic.
It prints the log and then safely exits the program.
It exits the program.

Example of func Fatal in Go (Golang)

Relevant excerpt from the article:

Fatal is equivalent to Print() followed by a call to os.Exit(1).

Pytanie 32. Which is a valid Go time format literal?

“2006-01-02”
“YYYY-mm-dd”
“y-mo-d”
“year-month-day”

func Time in Go

Relevant excerpt from the article:

Year: "2006" "06"
Month: "Jan" "January" "01" "1"
Day of the week: "Mon" "Monday"
Day of the month: "2" "_2" "02"
Day of the year: "__2" "002"
Hour: "15" "3" "03" (PM or AM)
Minute: "4" "04"
Second: "5" "05"
AM/PM mark: "PM"

Pytanie 33. How should you log an error (err)

log.Error(err)
log.Printf("error: %v", err)
log.Printf(log.ERROR, err)
log.Print("error: %v", err)

Wyjaśnienie: There is defined neither log.ERROR, nor log.Error() w log package in Go; log.Print() arguments are handled in the manner of fmt.Print(); log.Printf() arguments are handled in the manner of fmt.Printf().

Pytanie 34. Which file names will the `go test` command recognize as test files?

any that starts with test
any files that include the word test
only files in the root directory that end in _test.go
any that ends in _test.go

Test packages in go command in Go: ‘Go test’ recompiles each package along with any files with names matching the file pattern “*_test.go”.
Add a test in Go

Pytanie 35. What will be the output of this code?

ch := make(chan int)
ch <- 7
val := <-ch
fmt.Println(val)

0
It will deadlock
It will not compile
2.718

Go Playground share, wyjście:

fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan send]:
main.main()
 /tmp/sandbox2282523250/prog.go:7 +0x37

Program exited.

Pytanie 36. What will be the output of this program?

ch := make(chan int)
close(ch)
val := <-ch
fmt.Println(val)

It will deadlock
It will panic
0
NaN

The Go Programming Language Specification “Receive operator”, Relevant excerpt from the article:

A receive operation on a closed channel can always proceed immediately, yielding the element type’s zero value after any previously sent values have been received.
Go Playground share, wyjście:

0

Program exited.

Pytanie 37. What will be printed in this code?

var stocks map[string]float64 // stock -> price
price := stocks["MSFT"]
fmt.Printf("%f\n", price)

0
0.000000
The code will panic
NaN

Go Playground share, wyjście:

0.000000

Program exited.

Pytanie 38. What is the common way to have several executables in your project?

Have a cmd directory and a directory per executable inside it.
Comment out main.
Use build tags.
Have a pkg directory and a directory per executable inside it.

Pytanie 39. How can you compile main.go to an executable that will run on OSX arm64 ?

Set GOOS to arm64 and GOARCH to darwin.
Set GOOS to osx and GOARCH to arm64.
Set GOOS to arm64 and GOARCH to osx.
Set GOOS to darwin and GOARCH to arm64.

Praca z zestawieniem materiałów

Q40. What is the correct syntax to start a goroutine that will `print Hello Gopher!`?

go(fmt.Println("Hello Gopher!"))
go func() { fmt.Println("Hello Gopher!") }
go fmt.Println("Hello Gopher!")
Go fmt.Println("Hello Gopher!")

Example of start a goroutine

Pytanie 41. If you iterate over a map in a for range loop, in which order will the key:value pairs be accessed?

in pseudo-random order that cannot be predicted
in reverse order of how they were added, last in first out
sorted by key in ascending order
in the order they were added, first in first out

Odniesienie

Pytanie 42. What is an idiomatic way to customize the representation of a custom struct in a formatted string?

There is no customizing the string representation of a type.
Build it in pieces each time by calling individual fields.
Implement a method String() strunowy
Create a wrapper function that accepts your type and outputs a string.

Odniesienie

Pytanie 43. How can you avoid a goroutine leak in this code?

func findUser(ctx context.Context, login string) (*User, error) {
    ch := make(chan *User)
    go func() {
            ch <- findUserInDB(login)
    }()

    select {
    case user := <-ch:
            return user, nil
    case <-ctx.Done():
            return nil, fmt.Errorf("timeout")
    }
}

Use a sync.WaitGroup.
Make ch a buffered channel.
Add a default case to the select.
Use runtime.SetFinalizer.

Odniesienie

Relevant excerpt from the article:

The simplest way to resolve this leak is to change the channel from an unbuffered channel to a buffered channel with a capacity of 1. Now in the timeout case, after the receiver has moved on, the Goroutine will complete its send by placing the *User value in the channel then it will return.

44. What will this code print?

var i int8 = 120
i += 10
fmt.Println(i)

-126
0
NaN
130

Go Playground example, wyjście:

-126

Program exited.

45. Given the definition of worker below, what is the right syntax to start a goroutine that will call worker and send the result to a channel named ch?

func worker(m Message) Result

go func() {
    r := worker(m)
    ch <- r
}

go func() {
    r := worker(m)
    r -> ch
} ()

go func() {
    r := worker(m)
    ch <- r
} ()

go ch <- worker(m)

Go Playground example

Pytanie 46. In this code, which names are exported?

package os

type FilePermission int
type userID int

FilePermission
żadna z tych odpowiedzi
FilePermission and userID
userID

Odniesienie 1 Odniesienie 2

Pytanie 47. Which of the following is correct about structures in Go?

Structure is another user defined data type available in Go programming, which allows you to combine data items of different kinds.
Structures are used to represent a record
To define a structure, you must use type and struct statements.
Wszystkie powyższe

Pytanie 48. What does the built-in `generate` command of the Go compiler do?

It provides subcommands sql, json, yaml, and switches --schema oraz --objects to generate relevant code.
It looks for files with names that end with _generate.go, and then compiles and runs each of these files individually.
It scans the projects source code looking for //go:generate Konstruuj i analizuj segmenty kodu, które wykonują iterację, and for each such comment runs the terminal command it specifies.
It has subcommands mocks oraz tests to generate relevant .go source files.

Generate Go files by processing source

Pytanie 49. Using the time package, how can you get the time 90 minutes from now?

time.Now().Add(90)
time.Now() + (90 * time.Minute)
time.Now() + 90
time.Now().Add(90 * time.Minute)

func (Czas) Add example

Q50. A program uses a channel to print five integers inside a goroutine while feeding the channel with integers from the main routine, but it doesn’t work as is. What do you need to change to make it work?

Add a close(ch) natychmiast po wg.Wait().
Add a second parameter to make(chan, int), np. make(chan int, 5).
Remove the use of unnecessary WaitGroup dzwoni, np. all lines that start with wg.
Move the 7-line goroutine immediately after wg.Add(1) to a line immediately before wg.Wait().

Odniesienie

Relevant excerpt from the article:

The simplest way to resolve this leak is to change the channel from an unbuffered channel to a buffered channel with a capacity of 1. Now in the timeout case, after the receiver has moved on, the Goroutine will complete its send by placing the *User value in the channel then it will return.

Pytanie51. After importing `encoding/json`, how will you access the `Marshal` funkcjonować?

encoding.json.Marshal
encoding/json.Marshal
Marshal
json.Marshal

encoding/json#Marshal example

Pytanie52. What are the two missing segments of code that would complete the use of `context.Context` to implement a three-second timeout for this HTTP client making a GET request?

package main

import (
        "context"
        "fmt"
        "net/http"
)

func main() {
        var cancel context.CancelFunc
        ctx := context.Background()

        // #1: <=== What should go here?

        req, _ := http.NewRequest(http.MethodGet,
                "https://linkedin.com",
                nil)

        // #2: <=== What should go here?

        client := &http.Client{}
        res, err := client.Do(req)
        if err != nil {
                fmt.Println("Request failed:", err)
                return
        }
        fmt.Println("Response received, status code:",
                res.StatusCode)
}

      ctx.SetTimeout(3*time.Second)
      req.AttachContext(ctx)

      ctx, cancel = context.WithTimeout(ctx, 3*time.Second); defer cancel()
      req = req.WithContext(ctx)

      ctx, cancel = context.WithTimeout(ctx, 3*time.Second); defer cancel() #2: req.AttachContext(ctx)

      ctx.SetTimeout(3*time.Second)
      req = req.WithContext(ctx)

Pytanie53. If you have a struct named Client defined in the same .go file as the statement, how do you export a variable with a default value so the variable is accessible by other packages?

```
let Default := new Client()
```
```
public default = &Client()
```
```
var Default = &Client{}
```
```
export default := new Client{}
```

Pytanie54. This program outputs `{Master Chief Spartan Protagonist Halo}`. How would you get it to output `Master Chief - a Spartan - is the Protagonist of Halo` zamiast?

package main

import "fmt"

type Character struct{
        Name  string
        Class string
        Role  string
        Game  string
}

func main() {
        mc := Character{
                Name: "Master Chief",
                Class: "Spartan",
                Role: "Protagonist",
                Game: "Halo",
        }
        fmt.Println(mc)
}

// Replace
// fmt.Println(mc)
// with this:

fmt.Printf("(?P<Name>) - a (?P<Class>) - is the (?P<Role>) of (?P<Game>)", mc)

// Replace
// fmt.Println(mc)
// with this:
fmt.Println(mc, func(c Character) string {
      return c. Name + " - a " + c.Class + " - is the " + c.Role + " of " + c.Game
})

// add this to the package `main`

func (c Character) String() string {
      return fmt.Sprintf("%s - a %s - is the %s of %s", c.Name, c.Class, c.Role,c.Game)
}

 // add this to the package `main`

func (c Character) OnPrint() {
      fmt.Println("{{c.Name}} - a {{c.Class}} - is the {{c.Role}} of {{c.Game}}")
}

fmt#Stringer

Pytanie55. How would you implement a working `Append()` method for `Clients`?

package main

type Client struct {
  Name string
}
type Clients struct {
  clients []*Client
}
func main() {
  c:= &Clients{clients.make([]*Client,0)}
  c.Append(&Client{Name: "LinkedIn API})
}

func (cc *Clients) Append(c *Client) {
  cc.clients = append(cc.clients, c)
}

func (cc *Clients) Append(c *Client) {
  cc.append(c)
}

func (cc Clients) Append(c Client) {
  cc.clients = append(cc.clients, c)
}

func (cc *Clients) Append(c Client) {
  cc.clients.append(c)
}

Pytanie56. How would you recover from a `panic()` thrown by a called function without allowing your program to fail assuming your answer will run in the same scope where your function call will experience the panic?

Wrap the function call in an anonymous function with a return type of panic, remembering to invoke the anonymous function by suffixing it with () then introspecting the returned panic instance to handle the error.
T-SQL w SQL Server dla początkujących try{ ... } to wrap the code calling the function and then handle the error within the catch{ ... }.
T-SQL w SQL Server dla początkujących defer func { ... }() before the function call with the error and then handle the panic inside the anonymous function.
Prefix the function call with @ to force return the panic as an error value and then handle the error just as you would an error returned by any function.

Pytanie57. What will this code print?

var n int
fmt.Println (n)

0
nil
a random value
1

This is because in Go, when a variable is declared but not explicitly initialized, it is assigned a default zero value based on its type. For integers like n, the zero value is 0.

Pytanie58. When creating a formatted string, which verb should you use to call the String () string method of a custom type?

%s
%b
%Rząd Burkina Faso dokonuje przeglądu swojego planu dla sektora edukacji
%strunowy

In Go, the %s verb is used to format a string. When used with a custom type that has a String() method defined, the String() method will be automatically called and its return value will be used in the formatted string.

Pytanie59. Which is not a valid value for layout when calling time. Ale już ( ) . Format ( układ)?

time.REC3339
“1970-01-01”
“Jan 2nd 2006”
time.Kitchen

time#Time.Format

According to the documentation, the value 1 oraz 01 will represent the current month.

each layout string is a representation of the time stamp,
	Jan 2 15:04:05 2006 MST
An easy way to remember this value is that it holds, when presented in this order, the values (lined up with the elements above):
	  1 2  3  4  5    6  -7

Q60. How would you signal to the Go compiler that the Namespace struct must implement the JSONConverter interface? This question assumes the answer would be included in the same package where Namespace is declared.

var_JSONConverter = nil. (*Mistrz programowania w C++)
var_JSONConverter = (*Mistrz programowania w C++) (nil)
type Namespace struct { implements JSONConverter // The rest of the struct declaration goes here }
type Namespace struct { JSONConverter // The rest of the struct declaration goes here }

This syntax creates a variable _ with the type of JSONConverter and assigns to it a value of (*Mistrz programowania w C++)(nil). This essentially checks that the Namespace struct satisfies the JSONConverter interface by ensuring that it can be assigned to a variable of type JSONConverter.

Q61. Which statement about typing and interfaces is false?

A method signature is the combination of a method name and the type(s) of its declared parameter(s) and return value(s).
A struct must explicitly declare using the implements keyword that its instances can be used wherever a variable, parameter, and/or return value is typed for the declared interface.
An interface declares a list of methods and their signatures that a type must implement to be compatible with values typed for that interface.
Variable, parameters, and return values must be “typed” jako jeden z 1) a built-in type, 2) a type alias, 3) a derived type, 4) a composite type, lub

an interface.

In Go, a type automatically satisfies an interface if it implements all the methods of that interface. There is no need to explicitly declare that a struct implements an interface using a specific keyword.

Q62. How would you complete this program to generate the specified output, assuming the SQL table

===[Output]================
1: &{GameId:1 Title:Wolfenstein YearReleased:1992}
2: &{GameId:2 Title:Doom YearReleased:1993}
3: &{GameId:3 Title:Quake YearReleased:1996}

===[main.go]================
package main

import (
        "database/sql"
        "fmt"
        _ "github.com/go-sql-driver/mysql"
        "log"
)

type Game struct {
        GameId       int
        Title        string
        YearReleased int
}

func main() {

        conn, err := sql.Open("mysql",
                "john_carmack:agiftw!@tcp(localhost:3306)/idsoftware")

        if err != nil {
                panic(err)
        }
        defer func() { _ = conn.Close() }()

        results, err := conn.Query("SELECT game_id,title,year_released FROM games;")
        if err != nil {
                panic(err)
        }
        defer func() { _ = results.Close() }()

        // #1 <=== What goes here?

        for results.Next() {
                var g Game

                // #2 <=== What goes here?

                if err != nil {
                        panic(err)
                }

                // #3 <=== What goes here?

        }

        for i, g := range games {
                fmt.Printf("%d: %+v\n", i, g)
        }

}

#1: games := make([]*Game, results.RowsAffected())
#2: g, err = results.Fetch()
#3: games[results.Index()] = &g

#1: games := []Game{}
#2: g, err = results.Fetch()
#3: games = append(games,g)

#1: games := map[int]Game{}
#2: err = results.Scan(&g)
#3: games[g.GameId] = g

#1: games := make(map[int]*Game, 0)
#2: err = results.Scan(&g.GameId, &g.Title, &g.YearReleased)
#3: games[g.GameId] = &g

Q63. Fill in the blanks

Test files in Go must _.
Individual tests are identified by _.
You can run subtests by __.
You log the error and mark the test failed by _.

be stored in a /test/subdirectory of that package
functions accepting a testing.Tester parameter
writing functions with names matching ^Subtest
powołanie testing.AssertionFailed
end in _test.go
function names matching ^Test[A-Z]
powołanie t.Run()
powołanie t.Errorf()
begin with test_
functions matching [a-z]Test$
powołanie testing.Subtest()
allowing testing.Assert() to fail its assertion
be stored in /test/ root subdirectory for the project
functions accepting a testing.Test parameter
passing closures to testing.AddSubtest()
returning an error from the function

Q64. Which type is a rune an alias for?

char
byte
int32
strunowy

Strings, bajty, runes and characters in Go

Relevant excerpt from the article:

The Go language defines the word rune as an alias for the type int32, so programs can be clear when an integer value represents a code point.

Q65. When can you use the := syntax to assign to multiple variables? Na przykład:

x, err := myFunc()

if it at least has not been declared in that lexical block
at all times, as it will overwrite existing variables
if no variables of those names is accessible
if none of the variables exist in that lexical block

Short variable declarations

Q66. How can You view the profiler output in cpu.pprof in the browser?

go pprof -to SVG cpu.prof
go tool pprof -http=:8080 cpu.pprof (PRAWDA)
go tool pprof cpu.pprof
go tool trace cpu.pprof

Q67. When does a variable of type interface{} evaluate to nil?

It has been assingned a dynamic type whose value is nil. (PRAWDA)
It has been explicitly set to nil.
It has not been assigned a dynamic type.
It can not evaluate to nil.

Q68. What value does a string variable hold if it has been allocated but not assigned?

nil
undefined
zero
“”

If a string variable has been allocated but not assigned a value, its default value is an empty string “”. In Go, uninitialized string variables are automatically assigned the zero value for their respective type, which for strings is an empty string.

Q69. Which built-in function is used to stop a program from continuing?

panic
There is no such function.
raiseException
Wyjście

The built-in function used to stop a program from continuing is panic(). Po co to robić sam, skoro mam lepsze rzeczy do roboty panic() jest nazywany, it triggers a panic, which stops the normal execution flow of the program and begins panicking. If the panic is not recovered, the program terminates.

Q70. What will the output be?

a,b := 1, 2
b,c:= 3, 4
fmt.Println(a, b, c)

1 3 4
1 2 3
1 2 4
It will not compile.

Go Playground Example

Q71. What is the operator for a logical AND condition?

+
oraz
&&
||

Q72. What is an anonymous function in Go?

A function with no return type.
A function with no parameters.
A function without a name.
A function declared inside another function.

Q73.Which keyword is used to declare an anonymous function in Go?

func
lambda
func()
anonymous

Q74. What is the main advantage of using anonymous functions in Go?

They always have better performance than named functions.
They can have multiple return values.
They can be defined inline where they are used.
They have a shorter syntax than named functions.

Wyjaśnienie: they can be defined inline where they are used, offering more flexibility in code organization.

Q75. What is the syntax for calling an anonymous function immediately after its declaration in Go?

functionName(){}
call functionName(){}
func(){}()
execute func(){}

odniesienie

Q76. Which types can Go developers define methods for?

all named types not built-in to Go, such as type Example int but not int, type Example struct{...} but not struct, etc.
only types named struct, map, and slice, such as type Example struct{…}
only types named struct, such as type Example struct{...}
all types

Methods can be defined for any named type that is not a built-in type. When you create a new type using a type declaration, it becomes a named type, and you can define methods specific to that type. Jednakże, methods cannot be directly attached to built-in types like int, strunowy, itp. odniesienie

Autor

Helena Bassy

utrudnisz uczenie się, a nie zapamiętywanie, I'm Helena, autor bloga, którego pasją jest publikowanie wnikliwych treści w niszy edukacyjnej. Wierzę, że edukacja jest kluczem do rozwoju osobistego i społecznego, i chcę dzielić się moją wiedzą i doświadczeniem z uczniami w każdym wieku i na każdym poziomie. Na moim blogu, znajdziesz artykuły na takie tematy, jak strategie uczenia się, Edukacja online, doradztwo zawodowe, i więcej. Chętnie przyjmę także uwagi i sugestie od moich czytelników, więc nie wahaj się zostawić komentarza lub skontaktować się ze mną w dowolnym momencie. Mam nadzieję, że czytanie mojego bloga sprawi Ci przyjemność i uznasz go za przydatny i inspirujący.
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