30+ Golang Interview Questions And Answers
Golang, also known as Go, is a robust system-level language created by Google. It's used for programming across large-scale network servers and big distributed systems. Golang is prized for its simplicity, efficiency, and reliability. Preparing for a Golang interview involves understanding its basic syntax, concepts, and also confronting more complex problems. Below is a curated set of interview questions for Golang enthusiasts at different skill levels, from beginners to those with advanced knowledge.
Most asked Golang interview questions
Beginners
1.
What is a goroutine and how is it different from a thread?
1.
What is a goroutine and how is it different from a thread?
A goroutine is a lightweight thread managed by the Go runtime. Unlike a regular OS thread, goroutines require less memory, and their stack can grow and shrink according to the needs of the application.
2.
Explain the use of the 'defer' keyword in Go.
2.
Explain the use of the 'defer' keyword in Go.
The 'defer' keyword is used to ensure that a function call is performed later in a program’s execution, usually for purposes of cleanup. 'defer' is often used where you would use ensure or finally in other languages.
3.
What is a slice in Go and how does it differ from an array?
3.
What is a slice in Go and how does it differ from an array?
A slice is a segment of an array. Slices are indexable and have a length. Unlike arrays, their size is dynamic - they can grow and shrink as needed.
4.
How do you get the length of a slice in Go?
4.
How do you get the length of a slice in Go?
You use the len() function to get the length of a slice.
5.
What package is used for I/O in Go?
5.
What package is used for I/O in Go?
The 'io' and 'fmt' packages are primarily used for input and output operations in Go.
6.
What does the following code print?
package main
import "fmt"
func main() {
msg := "Hello, world!"
fmt.Println(msg)
}
6.
What does the following code print?
package main
import "fmt"
func main() {
msg := "Hello, world!"
fmt.Println(msg)
}It prints the message: Hello, world!
7.
How would you create a map in Go?
7.
How would you create a map in Go?
You can create a map using the make function: make(map[keyType]valueType).
8.
Can you return multiple values from a function in Go?
8.
Can you return multiple values from a function in Go?
Yes, functions in Go can return multiple values.
9.
What is the zero value in Go?
9.
What is the zero value in Go?
The zero value is the default value that a variable gets if you don’t assign a value to it. It's 0 for numbers, false for booleans, "" (the empty string) for strings, and nil for pointers, functions, interfaces, slices, channels, and maps.
10.
Does Go support object-oriented programming?
10.
Does Go support object-oriented programming?
Go does not support the classical object-oriented programming model, but it does have types and methods that allow you to apply some object-oriented principles.
11.
What are channels and how are they used?
11.
What are channels and how are they used?
Channels are a concurrency primitive that lets you communicate between goroutines and synchronize their execution.
12.
What does 'go' keyword do?
12.
What does 'go' keyword do?
The 'go' keyword is used to start a new goroutine.
13.
How do you specify if a channel is read-only or write-only?
13.
How do you specify if a channel is read-only or write-only?
You signal a channel's direction using arrow syntax: a chan<- type is send-only, and a <-chan type is receive-only.
14.
What is a pointer and how would you create one in Go?
14.
What is a pointer and how would you create one in Go?
A pointer is a variable that stores the memory address of another variable. In Go, you can create a pointer using the & operator to get the address of a variable.
15.
Can you modify the underlying array of a slice in Go?
15.
Can you modify the underlying array of a slice in Go?
Yes, if you have a slice of an array, you can modify the elements of the array through the slice.
Advanced
1.
Explain the difference between buffered and unbuffered channels.
1.
Explain the difference between buffered and unbuffered channels.
A buffered channel has a capacity and allows sends and receives to happen asynchronously; sends do not block if the channel's buffer is not full, and receives do not block if it's not empty. Unbuffered channels do not have this capacity and they are synchronous; sends block until a receive is ready and vice versa.
2.
How do you handle panics in Go?
2.
How do you handle panics in Go?
You can handle a panic using the recover() function within a deferred function. When the enclosing function panics, the deferred function runs and can recover control.
3.
What is the purpose of an interface in Go?
3.
What is the purpose of an interface in Go?
An interface is a type that specifies a set of method signatures. A value of interface type can hold any value that implements those methods.
4.
If Go does not have inheritance, how can you extend the functionality of a type?
4.
If Go does not have inheritance, how can you extend the functionality of a type?
You can use type embedding to 'simulate' inheritance by including a type as an anonymous field within another struct. The methods of the embedded type become part of the outer type.
5.
Explain the concept of a select block in Go.
5.
Explain the concept of a select block in Go.
A select block lets a goroutine wait on multiple communication operations. A select blocks until one of its cases can run, then it executes that case. It's similar to a switch statement but for channels.
6.
What is the output of the following code?
package main
import (
"fmt"
"sync"
)
func main() {
var count int
var lock sync.Mutex
for i := 0; i < 1000; i++ {
go func() {
lock.Lock()
count++
lock.Unlock()
}()
}
fmt.Println(count)
}
6.
What is the output of the following code?
package main
import (
"fmt"
"sync"
)
func main() {
var count int
var lock sync.Mutex
for i := 0; i < 1000; i++ {
go func() {
lock.Lock()
count++
lock.Unlock()
}()
}
fmt.Println(count)
}The output is non-deterministic because the main goroutine may run the fmt.Println function before the other goroutines finish executing.
7.
How can you implement a constant time-out pattern when listening on a channel?
7.
How can you implement a constant time-out pattern when listening on a channel?
You can use the time.After function which returns a channel that blocks for the specified duration and then sends the current time.
8.
What are Go's guidelines for formatting code?
8.
What are Go's guidelines for formatting code?
Go provides an official formatting tool called gofmt, which automatically formats Go source code according to the style guidelines in the Go community.
9.
What are some of the properties that make Go suitable for concurrent programming?
9.
What are some of the properties that make Go suitable for concurrent programming?
Its lightweight goroutine model, channels for communication and synchronization, the select statement, and a memory model designed to prevent race conditions make Go well-suited for concurrent programming.
10.
How does Go's garbage collector improve performance compared to other languages?
10.
How does Go's garbage collector improve performance compared to other languages?
Go's garbage collector is designed to be efficient and operate concurrently with the program, reducing pause times and keeping the application responsive.
11.
How do you structure error handling in Go?
11.
How do you structure error handling in Go?
You use built-in error type in function return values. It's idiomatic to handle errors by comparing them to nil, followed by handling the error case before proceeding with normal execution.
12.
What is the difference between 'new' and 'make' functions?
12.
What is the difference between 'new' and 'make' functions?
new(T) allocates memory for a new item of type T and returns a pointer, while make(T, args) is used for slices, maps, and channels and returns an initialized value of type T (not a pointer).
13.
Can you explain type assertion in Go?
13.
Can you explain type assertion in Go?
Type assertion is used to extract the underlying value of an interface. For example, value := interfaceVariable.(concreteType) asserts that interfaceVariable holds a value of concreteType and assigns it to value.
14.
How do you make sure that a goroutine completes its execution before the program terminates?
14.
How do you make sure that a goroutine completes its execution before the program terminates?
You can use a sync.WaitGroup to wait for goroutines to complete by incrementing a counter before starting a goroutine and decrementing it within the goroutine once it completes.
15.
What does the following code do and when might it panic?
package main
func main() {
var a []int
a[0] = 1
}
15.
What does the following code do and when might it panic?
package main
func main() {
var a []int
a[0] = 1
}The code tries to assign a value to the first element of a nil slice, which will cause a runtime panic since the slice hasn't been initialized with a size.
Golang Interview Tips
Understand the Question
-
When faced with a tough interview question, make sure you understand the question completely. Don't hesitate to ask the interviewer for clarification if something isn't clear. It's better to take a moment to fully grasp the question than to start off answering incorrectly. You can also repeat the question back to the interviewer in your own words to confirm that you got it right.
Stay Calm and Take Your Time
-
Keeping calm under pressure can help you think more clearly and methodically. If you're stumped, it's okay to take a short pause to collect your thoughts. Breath deeply and use the time to structure your answer logically. Rushing into an answer might lead to mistakes or unnecessary confusion.
Break Down the Problem
-
Tough questions are often tough because they seem overwhelming at first glance. Break them down into smaller, manageable parts, and address each part individually. If the question involves a complex problem, outline the steps you would take to solve it. This shows analytical thinking and structured problem-solving ability.
Think Aloud
-
Thinking out loud throughout your problem-solving process gives the interviewer insight into your thought process. It also helps them follow along with your reasoning. Speaking aloud can sometimes help you clear up your own confusion and reach clarity. If you reach a dead end, the interviewer might even offer hints or guide you back on track.
It's Okay Not to Know Everything
-
If you really don't know the answer to a question, it's okay to admit it. Be honest about what you do not know while expressing a willingness to learn or find out. You can also explain how you would go about finding the answer, thus demonstrating resourcefulness and initiative.
FAQs
How much does it cost to hire a Golang developer?
Costs vary depending on the developer's experience, but with FireHire, pricing starts at $45/hour for top-tier Golang developers. Read more: How much does it cost to hire a Golang developer?
How much does a go developer cost?
A Go developer can range in cost, yet FireHire offers competitive rates starting from $45/hour, delivering value without compromising on quality. Read more: How much does a go developer cost?
Are Golang developers in demand?
Yes, Golang's efficient performance and scalability has led to a surge in demand for skilled Golang developers across various industries. Read more: Are Golang developers in demand?
Why using FireHire for hiring Golang developers is the best choice?
FireHire stands out for its rigorously vetted senior developers, swift placement services (averaging 5 days), and a 30-day risk-free replacement guarantee, ensuring you get the best Golang talent for your needs.
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