TOP 20 GOLANG INTERVIEW QUESTIONS FOR PREPARATION
Golang, also known as Go, is a relatively new programming language that was created by Google developers Robert Griesemer, Rob Pike, and Ken Thompson in 2012. Golang is said to have come about as a result of frustration with the shortcomings of existing programming languages.
Go is a high-level, open-source programming language that was created with the goal of improving code efficiency without sacrificing simplicity or compile-time in order to help developers develop software applications more quickly. Companies such as Google, Apple, and Uber use Golang because of its demonstrated ability to reduce learning time, speed up code development, improve runtime efficiency, reduce bugs, and implement concurrency and garbage collection strategies, among other things.
1. In Golang, what is a variable’s static type declaration?
Static type variable declaration informs the compiler that there is only one variable with the given kind and name, allowing the compiler to proceed with another compilation without requiring complete knowledge of the variable. A variable declaration is only important during the compilation process; the compiler requires an actual variable declaration when connecting to the programme.
2. In Golang, what is a dynamic variable declaration?
The compiler must explain the type of the variable based on the amount transferred to it in a dynamic kind variable declaration. As a mandatory condition, the compiler does not require a variable to categorise statically.
3. How can we swap variables in Golang?
func swap(sw []int) {
for a, b := 0, len(sw)-1; a < b; a, b = a+1, b-1 {
sw[a], sw[b] = sw[b], sw[a]
}
}
func main() {
x := []int{3, 2, 1}
swap(x)
fmt.Println(x)
// Output: [1 2 3]
}
4. How do you check the type of a variable at runtime?
The Type Switch is the most efficient way to determine the type of a variable at runtime. The Type Switch assesses variables based on their type rather than their value. Each Switch has at least one case that acts as a conditional statement, as well as a default case that runs if none of the other cases are true.
You could, for example, create a Type Switch that checks whether the interface value I is of the type int or string:
import "fmt"
func do(i interface{}) {
switch v := i.(type) {
case int:
fmt.Printf("Double %v is %v\n", v, v*2)
case string:
fmt.Printf("%q is %v bytes long\n", v, len(v))
default:
fmt.Printf("I don't know type %T!\n", v)
}
}
func main() {
do(21)
do("hello")
do(true)
}
5. What are the benefits of learning Golang? What are the benefits of Golang over other programming languages?
The Go language is based on the maxim “maximum effect with minimum effort.” Every feature and syntax in Go was created with programmers in mind. The benefits of Go Language are as follows:
Simple and Understand: Go is a very simple language to learn and understand. There are no features that are unnecessary. Regardless of the size of the codebase, every single line of Go code is very easily readable and thus understandable. Go was designed with readability, maintainability, and simplicity in mind.
Standard Powerful Library:Go supports all standard libraries and packages that make writing code easier and more efficient.
Concurrency support: Using Go Routines or channels, Go provides excellent concurrency support. Concurrency is implemented using efficient memory management strategies and multi-core processor architecture.
Static Type Checking: Go is a powerful and statically typed programming language. Every variable in a statically typed system has a type assigned to it. The data type cannot be changed once it has been created, and strongly typed means that type conversion is subject to rules and restrictions. This guarantees that the code is type-safe and that all type conversions are completed quickly. This is done to reduce the chances of runtime errors.
Easy to install Binaries: Binaries that are simple to install: Go supports generating binaries for applications that include all required dependencies. These binaries make it simple to install Go-based tools and applications without the need for a Go compiler, package managers, or runtimes.
Good Testing Support: Go provides excellent support for writing unit test cases alongside our code. There are libraries that help with code coverage and documentation generation.
6. What do you mean when you say “variable scope” in Go?
The variable scope is the section of the programme in which the variable can be accessed. In Go, every variable is statically scoped (meaning that the scope of a variable can be determined at compile time), which means that the scope is declared at the time of compilation. In Go, there are two types of scopes:
Local variables are variables that are declared within a function or a block and can only be accessed within those entities.
Global variables are variables that are declared outside of a function or block and are accessible throughout the source code.
7. What do you understand by goroutine in Golang?
A goroutine is a Golang function that runs concurrently or parallelly with other Golang functions. They can be thought of as a lightweight thread that can execute independently and concurrently with other routines. Go Runtime is in charge of all goroutines. Golang uses goroutines to achieve concurrency.
The main goroutine in Golang is the main function of the main package. It’s where all the other goroutines begin. These goroutines can initiate their own goroutines. The programme is complete once the main goroutine has completed its execution.
Simply specifying the go keyword before the method call will start a goroutine. The method will now be called as a goroutine and executed.
package main
import (
"fmt"
"time"
)
func main() {
go sampleRoutine()
fmt.Println("Started Main")
time.Sleep(1 * time.Second)
fmt.Println("Finished Main")
}
func sampleRoutine() {
fmt.Println("Inside Sample Goroutine")
}
The sampleRoutine() function is called in this code by specifying the keyword go before it. When a function is called a goroutine, the call is returned to the next line of the programme statement, which is why “Started Main” is printed first and the goroutine is scheduled to run in the background concurrently. The sleep statement guarantees that the goroutine is scheduled before the main goroutine finishes. The following is the code’s output:
Started Main
Inside Sample Goroutine
Finished Main
8. Describe pointers in Go.
Any variable’s address is stored in a pointer variable. In Golang, pointers are also known as special variables. There are two types of operators in pointers:
The * operator, also known as a dereferencing operator, is used to access the value in the address, and the operator, also known as an address operator, is used to return the variable’s address.
9. In Go, what is a constant variable?
Constant, as the name implies, refers to a fixed value that does not change in a programming language. Once a constant variable’s value is defined, it must remain constant throughout the programme; we cannot change the value of a variable in the middle of a programme.
10. How do you join strings together?
The concatenation operator (+), which allows you to add strings like numerical values, is the simplest way to concatenate strings.
package main
import "fmt"
func main() {
// Creating and initializing strings
// using var keyword
var str1 string
str1 = "Hello "
var str2 string
str2 = "Reader!"
// Concatenating strings
// Using + operator
fmt.Println("New string 1: ", str1+str2)
// Creating and initializing strings
// Using shorthand declaration
str3 := "Welcome"
str4 := "Educative.io"
// Concatenating strings
// Using + operator
result := str3 + " to " + str4
fmt.Println("New string 2: ", result)
}
11. What are function closures, exactly?
A function closure is a value that refers to variables outside the body of the function. The function has access to the referenced variables and can assign values to them.
For example, adder() returns a closure, which is each bound to its own referenced sum variable.
package main
import "fmt"
func adder() func(int) int {
sum := 0
return func(x int) int {
sum += x
return sum
}
}
func main() {
pos, neg := adder(), adder()
for i := 0; i < 10; i++ {
fmt.Println(
pos(i),
neg(-2*i),
)
}
}
12. In Golang, how do we perform inheritance?
This is a trick question: Golang does not support inheritance because it does not support classes.
However, you can use composition to mimic inheritance behaviour by using an existing struct object to define a new object’s starting behaviour. The functionality of the new object can be extended beyond the original struct once it has been created.
type Animal struct {
// …
}
unc (a *Animal) Eat() { … }
func (a *Animal) Sleep() { … }
func (a *Animal) Run() { … }
type Dog struct {
Animal
// …
}
The Animal struct contains Eat(), Sleep(), and Run() functions. These functions are embedded into the child struct Dog by simply listing the struct at the top of the implementation of Dog.
13. What makes Golang so quick in comparison to other languages?
With its simple and efficient memory management and concurrency model, Golang is faster than other programming languages. Compilation of machine code is a quick and efficient process. Furthermore, the dependencies are linked to a single binary file, which eliminates server dependencies.
14. What is the GoPATH variable in Golang?
The GoPATH environment variable is employed to symbolise directories out of $GoROOT that combines the source for Go projects including their binaries.
15. What is the GoROOT variable in Golang?
GoROOT is a variable that determines wherever your Go SDK is located. You do not require to modify this variable except if you plan to use various Go versions. GoPATH is a variable that determines the root of your workspace.
16. Explain structures in Golang?
A struct or a structure of Golang is a user-defined variety that helps the group or combines items of various types into a single type, each real-world entity that holds some characteristics can be represented as a structure.
For example, an entity “student” has a name, roll no, and address. It gives the sense to group these three attributes into a single structure “student” as shown
type address struct
{
name string
Rollno int
address string
}
17. In Golang, what is a select statement?
The select statement in Go is similar to the switch statement, but the case statement in the select statement indicates communication, i.e. sent or received progress on the channel.
18. In Golang, what is CGo?
Go packages can use CGo to invite C code. cGo generates Go and C files that can be combined into a unique Go package from a Go source file with some unique features. That’s because C stands for “pseudo-package,” a unique name given to C’s namespace by cGo.
19. What are the advantages of learning the Golang programming language?
There are several compelling reasons to learn the Golang programming language. Let’s look at them one by one:
Simple to learn: The Golang programming language has a syntax that is similar to C, making it simple to learn for C or Java programmers. Golang’s syntax is smaller than other programming languages, making it easier to read and write programmes.
Concurrency: Using the Golang programming language, creating multithreading applications is simple.
Networking: At the production level, Go is ideal for writing networking applications such as TCP or HTTP servers. Go has parsing libraries that are simple to integrate with other services.
Tools: Because Golang is open-source, a large number of development tools are already available.
Speedy execution: Go’s language execution is extremely fast when compared to other programming languages.
20. What do you understand by each of the functions demo_func() as shown in the below code?
//DemoStruct definition
type DemoStruct struct {
Val int
}
//A.
func demo_func() DemoStruct {
return DemoStruct{Val: 1}
}
//B.
func demo_func() *DemoStruct {
return &DemoStruct{}
}
//C.
func demo_func(s *DemoStruct) {
s.Val = 1
}