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Top Go Interview Questions and Answers

By Umesh Singh
Last update: 08 Apr 2020, 44 Questions
Introduction to Golang
Go Interview Questions

An open-source programming language developed by Google, Go is designed for building fast and reliable applications. It is a statically-typed language that has a similar syntax to C.  This information has been asked quite a few times recently in Golang interview questions. Some of its main features include dynamic typing, rich library, a documentation engine called GoDoc that is used by the entire Go community, static code analysis, and built-in testing tools that are simple and efficient.

Go Programming
What is Golang? It is designed for building fast and reliable applications. It is a statically-typed language that has a similar syntax to C. Go is also known as Golang.
What is the latest version of Go? Go 1.13 released on March 2020.
Created By It is designed at Google and developed by Robert Griesemer, Rob Pike, and Ken Thompson.
Written in The former was written in C but now written in Go itself.
Official Website https://golang.org

Best Golang Interview Questions And Answers

1. How are interfaces implemented in Golang?

Golang language interfaces are different from other languages. In Golang, type implements an interface through the implementation of its methods. There are no explicit declarations or no “implements” keyword.

Example

                                                    

package main
import "fmt"
type I interface {
   M()
}
type T struct {
   S string
}
// This method means type T implements the interface I,
// but we don't need to explicitly declare that it does so.
func (t T) M() {
   fmt.Println(t.S)
}
func main() {
  var i I = T{"hello"}
  i.M()
}

2. How to swap two values in golang?

package main
import "fmt"
func main() {
   fmt.Println(functionByBestInterviewQuestion())
}

func functionByBestInterviewQuestion() []int {
   a, b := 15, 10
   b, a = a, b
   return []int{a, b}
}

3. Why Golang is fast?

Golang's small syntax and concurrency model make it a without a doubt speedy programming language. Golang is compiled to machine code and its compilation system is very fast. Go additionally hyperlinks all the dependency libraries into a single binary file as a consequence putting off the dependency on servers.

4. How do I check if an array is empty in Golang?

To check if the array is empty follow these steps:

Check with the builtin len() function, for example, len(slice) <= 0. If the array is empty, skip the for a loop.

r := whatever()
if len(r) > 0 {
   // do what you want
}

5. What are the benefits of Golang?
  • Concise, simple to work and Scalable
  • Built-in support for other applications
  • Good speed across platforms like OS X, Linux, and Windows.
  • Ability to cross-compile the application to run on different devices than the ones used for development
  • Automatic management of memory
6. What is workspace?

It is a directory hierarchy with three directories – src, pkg and bin - at its root that contain the Go code. The "src" directory includes source files, the "pkg" directory contains objects, and the "bin" directory contains commands.

Note: This information is usually asked in golang interview questions.

7. What are channels and how can you use them in Golang?

In Golang, a channel is a communication object which uses goroutines to communicate with each other. Technically, it is a data transfer pipe in which data can be transferred into or read from.

8. What is goroutine?

It is a function that runs concurrently with other functions. If you want to stop it, you will have to pass a signal channel to the goroutine, which will push a value into when you want the function to finish.

Example

                                                    

Quit : = make (chan bool) 
       go func ( ) { 
            for  { 
                 select { 
                       case <- quit: 
                       return 
                      default 
                        // do other stuff 
                } 
           } 
    }() 
   // Do stuff 
   // Quit goroutine 
Quit <- true 

9. Is Golang multithreaded?

Yes, Golang supports multithreading. Moreover, its design is based on multithreading.

10. What is meant by L value and R value in Golang?

Rvalue

  • Shows on assignment operator's right side.
  • Always assigned to lvalue.

Lvalue

  • Shows on assignment operator's left side.
  • Designated to a variable and not a constant.
11. How will you access command line arguments in a GO program?

The command line argument can be accessed using the os.Args variables.

For instance:
Package main
import (
  “fmt”
   “OS”
)
func main () {
   fmt.Println(len(os.Args), os.Args)
}

12. What is CGO Golang?

In Golang, the Cgo lets all the Go packages call a C code. With a Go source file written on some special features, the cgo makes an output in Go and C files which can be then combined into a single Go package bundle.

13. What is difference between concurrent and parallel in Golang?

Concurrency potential that two or extra calculations manifest inside the identical time frame, and there is usually some kind of dependency between them. Parallelism capacity that two or extra calculations show up simultaneously.

14. What is Shadowing?

In Golang, a shadowed variable is one which is declared in an inner scope having the same name and type as a variable in the outer scope. Here, the outer variable is mentioned after the inner variable is declared.

15. What is a string literal?

It refers to a string constant which is obtained by concatenating an arrangement of characters. String literals are of two types - Raw string literals and Interpreted string literals.

16. Why does my Go process use a lot of virtual memory?

The Go memory allocator preserves a significant portion of virtual memory for allocations, which is local to the specific Go process.

17. What is concurrency Golang?

Generally, large programs are made of many multiple small subprograms. For example, a server handles multiple requests made via web browsers and serves HTML web pages in response. In this case, each request made is considered as a small program.

Golang makes it possible to run smaller components of each of these programs simultaneously through concurrency. It has extensive support for concurrency using goroutines and channels

18. How is testing performed in GO?

To test on Golang, follow these steps:

  • Create a file and end it with _test.go.
  • This file should contain the TestXxx functions as described.
  • Now, put this file in the same package as the one which is being tested.
  • This file will now be included in the “go test” command.
19. What is the difference between Gopath and Goroot?
GOPATH GOROOT
This must be set in order to get, develop and install packages outside the standard Golang tree. Must be set only when installing to a specific custom location.
21. What is the GOPATH environment variable? It specifies the workspace's location. It is essential to set this environment variable while developing the Go code.
22. What are the built-in supports?

Here are some of the built-in supports:

  • Container: container/list,container/heap
  • Web Server: net/http
  • Cryptography: Crypto/md5 ,crypto/sha1
  • Compression: compress/ gzip
  • Database: database/sql
23. What is the usage of break statement, continue statement and goto statement?

Break statement: It terminates the “for” loop or switch statement and transfers execution following the “for” loop or switch.

Continue statement: It helps the loop to omit the remainder of its body and retest before repeating.

Goto statement: It transfers control to the statement

24. What are “packages”?

Every GO program is built of packages that are used to organize source code for readability and reusability. Packages make it easy to maintain applications. The abbreviation for a package is “fmt”.

26. What is range keyword?

It is used for loop to iterate over items of slice array, map or channel.

27. How can an entry be deleted from a map? Use the delete () function to delete an entry. It requires a map and the corresponding key that has to be deleted.
28. How can variable type be checked at the runtime?

A particular type known as type switch is used to check variable type at runtime and switch.

29. What are nil Pointers?

When a pointer is assigned “nil”, it called a nil pointer. It is a constant with a “zero” value defined in standard libraries.

30. How will you document libraries?

Godoc extracts package documentation from the source code that can be utilized on the command line or the web. An instance is golang.org/pkg/.

31. How is actual parameter different from the formal parameter?

Actual parameters: Parameters that are sent to the function at the calling end.

Formal Parameters: Parameters that are at the receiving of the function definition.

32. What is the difference between make and new?
  • New assignes the memory.
  • Make initializes map, slice, and channel types.
33. List the Looping constructs in Go language.

A loop statement allows programmers to execute a statement multiple times. Here is a general type of loop statement used in the majority of programming languages:

 

Loop Control Statements: These statements change execution from the typical sequence. When an implementation leaves a scope, every programmed object gets diminished.

The Infinite Loop: A loop will turn into an infinite loop if its condition is never false. It is possible to create endless loops by keeping the conditional expression empty.

34. What is a modular programming language?

It is a strategy for creating software by separating the functionality of a program into a different independent and exchangeable modules that are clubbed together to achieve the final software.

This is an essential topic in GO interview questions and Answers.

35. What is slice?

Go Array allows programmers to define factors that can hold information of a similar kind yet not give any strategy for building size or for getting a sub-exhibit. Slice takes care of this limitation. It provides utility functions needed on Array and is a part of Go programming.

36. What is a structure?

It is one of the data types that allow programmers to combine data items of different types. There are two types of structure - type and struct. Once you set up a structure, you can use it to declare variables.

37. What are Interfaces?

It is a way to identify the behavior of objects. Developed with the help of “type” followed by the name and keyword, it is used to represent a pair by furnishing information stored in interface and pointer.

38. Why is Type assertion used?

It is used to check values that are held by interface type variable. It is also used to convert various GO types.

39. What is the syntax for creating a function?

func function_name( [parameter list] ) [return_types] {
     // the body of the function
}

40. How we can print type of a variable in Go Programming?

var x, y, z = 3, 4, "foo"
fmt.Printf("x is of type %Tn", x)

42. What is function closures in GO Pragramming?

It is a anonymous functions that can be used in dynamic programming.

43. What is token in GO Programming?

A token is either a keyword, an identifier, a constant, a string literal, or a symbol in GO Programming used.

Advantages
  • Concise, simple to work and Scalable
  • Built-in support for other applications
  • Good speed across platforms like OS X, Linux, and Windows.
  • Ability to cross-compile the application to run on different devices than the ones used for development
  • Automatic management of memory

Are you looking for Golang Interview Questions? As a developer, you would want to know the best possible Questions that you might be asked in your Job Interview.

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