Go Programming Language Interview Questions

This page provides answers to frequently asked Go programming language interview questions.

What is Go?

Go (also known as Golang) is an open-source programming language developed at Google, primarily designed for system programming. It aims for simplicity, reliability, and efficiency.

Why Use Go?

Go's open-source nature makes it easy to build simple, reliable, and efficient software.

Creators of Go

Go was designed by Robert Griesemer, Rob Pike, and Ken Thompson at Google Inc. in 2009.

Packages in Go

Go programs are built from packages. The main package is the entry point. Other packages are imported (e.g., using import "fmt").

Generic Programming in Go

Go does not directly support generic programming (like templates in C++ or generics in Java).

Case Sensitivity in Go

Yes, Go is case-sensitive.

String Literals in Go

String literals define string constants. There are two types:

  • Raw string literals: Enclosed in backticks (`...`), allowing newlines and special characters without escaping.
  • Interpreted string literals: Enclosed in double quotes ("..."), requiring escaping of special characters and not allowing newlines.

Go Workspace

A Go workspace is a directory structure with three subdirectories:

  • src: Contains Go source code organized into packages.
  • pkg: Stores compiled package objects.
  • bin: Contains executable commands.

Default Value of bool

The default value of a bool variable is false.

GOPATH Environment Variable

GOPATH specifies the location of the Go workspace. It must be set when developing Go code.

Advantages of Go

  • Fast compilation
  • Built-in concurrency support
  • Garbage collection
  • Safety features and CSP-style concurrency
  • Built-in support for strings and maps
  • First-class functions

Built-in Support in Go

Go provides built-in support for various areas, including:

  • Containers (container/list, container/heap)
  • Web servers (net/http)
  • Cryptography (crypto/md5, crypto/sha1)
  • Compression (compress/gzip)
  • Databases (database/sql)

Goroutines

A goroutine is a function that runs concurrently. To stop a goroutine, you can use a signal channel:

Example

quit := make(chan bool)
go func() {
    for {
        select {
        case <-quit:
            return
        default:
            // do other stuff
        }
    }
}()
// ... later ...
quit <- true // signal the goroutine to stop

Writing Multiple Lines in a String

Use a raw string literal (backticks):

Example

`line 1
line 2
line 3`

break Statement

Terminates a for loop or switch statement.

continue Statement

Skips the rest of the current iteration of a loop and proceeds to the next iteration.

goto Statement

Transfers control to a labeled statement.

for Loop Syntax

Go's for loop has multiple forms:

Syntax

for [condition | (init; condition; increment) | range] {
    // statements
}

Function Syntax

Syntax

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

Static vs. Dynamic Type Declaration

Static type declaration: The variable's type is known at compile time.

Dynamic type declaration: The variable's type is determined at runtime (using type inference or type assertions).

Printing Variable Type

Example

var a, b, c = 3, 4, "foo"
fmt.Printf("a is of type %T\n", a)

Pointers

A pointer holds the memory address of a variable.

Example

var x = 5
var p *int = &x // p now points to x
fmt.Println(*p) // Access the value pointed to by p

Pointer Representation

Pointers are represented using the * (asterisk) followed by the type.

Short Variable Declaration (:=)

The short variable declaration := can only be used inside functions.

Formatting Strings Without Printing

Use fmt.Sprintf():

Example

formattedString := fmt.Sprintf("at %v, %s", e.When, e.What)

Go Syntax (EBNF)

Go's syntax is defined using Extended Backus-Naur Form (EBNF).

Inheritance, Operator Overloading, Method Overloading, Pointer Arithmetic

Go does not support inheritance, operator overloading, method overloading, or pointer arithmetic.

Output of Example Code

The output of the provided example code (with constants i, j, k) is: 7 7 7

Go Interfaces

Interfaces define a set of methods. Any type that implements all the methods of an interface satisfies that interface.

Type Assertion

A type assertion retrieves a value of a specific type from an interface value.

Methods in Go

Methods are functions associated with a specific type (the receiver).

Default Values of Variables

  • Local variables: Zero value of their type.
  • Global variables: Zero value of their type.
  • Pointer variables: nil

Checking Variable Type at Runtime

Use a type switch.

Global Variables and Goroutines

Avoid global variables in programs with goroutines to prevent concurrency issues.

Modular Programming

Modular programming divides a program into smaller, reusable modules (functions) for improved efficiency and maintainability.

Further reading: