[Author: @mdimamhosen Date: 2025-04-19 Category: e.g., interview-qa/topic_name Tags: [go, concurrency, channels] ]

Variables are containers for storing data values

In Go, there are two ways to declare a variable

1. Use the var keyword, followed by variable name and type

package main
import ("fmt")

var name = "John Doe" // Variable One

func main() {
  var fruit = "Apple" // Variable Two
  fmt.Println(name)
  fmt.Println(fruit)
}

2. Use the := sign, followed by the variable value

package main
import ("fmt")

func main() {
  varOne := 100
  varTwo := 2
  fmt.Println(varOne)
  fmt.Println(varTwo)
}

Frequently Asked Questions (FAQs)

1. How do you declare a constant variable in Go?

Answer: Use the const keyword to declare a constant variable. Constants cannot be changed after they are declared.

package main
import ("fmt")

func main() {
  const pi = 3.14
  fmt.Println(pi)
}

2. Can you declare multiple variables in a single line?

Answer: Yes, you can declare multiple variables in a single line using the var keyword or := syntax.

package main
import ("fmt")

func main() {
  var x, y, z int = 1, 2, 3
  fmt.Println(x, y, z)
}

3. What is the zero value of a variable in Go?

Answer: Variables in Go are automatically assigned a zero value if not explicitly initialized.

package main
import ("fmt")

func main() {
  var number int
  fmt.Println(number) // Output: 0
}

4. How do you declare a global variable in Go?

Answer: Declare the variable outside of any function.

package main
import ("fmt")

var globalVar = "I am global"

func main() {
  fmt.Println(globalVar)
}

5. Can you reassign a value to a variable declared with var?

Answer: Yes, variables declared with var can be reassigned.

package main
import ("fmt")

func main() {
  var name = "John"
  name = "Doe"
  fmt.Println(name)
}

6. What happens if you declare a variable but do not use it?

Answer: Go does not allow unused variables and will throw a compile-time error.

package main
func main() {
  var unusedVar = 10 // This will cause an error
}

7. How do you declare a variable with a specific type?

Answer: Use the var keyword followed by the type.

package main
import ("fmt")

func main() {
  var age int = 25
  fmt.Println(age)
}

8. Can you declare a variable without initializing it?

Answer: Yes, but it will have a zero value.

package main
import ("fmt")

func main() {
  var name string
  fmt.Println(name) // Output: ""
}

9. How do you declare a variable in a block?

Answer: Use the var keyword inside a block.

package main
import ("fmt")

func main() {
  var (
    x int = 10
    y string = "Hello"
  )
  fmt.Println(x, y)
}

10. What is the difference between var and :=?

Answer: var can be used globally and allows explicit type declaration, while := is shorthand for local variable declaration and type inference.

package main
import ("fmt")

func main() {
  var name string = "John" // Explicit type
  age := 30 // Type inferred
  fmt.Println(name, age)
}