Declaration with var
- Go course
- Beginner
- Lesson 13/90
- 4 min
Learn to declare variables with the var keyword.
Declaration with var
The most basic way to declare a variable in Go is the var keyword. Writing var name int creates an integer variable named name and Go initialises it with its zero value.
You can state the type explicitly or, when you give an initial value, let Go infer it: var x = 5. Variables declared with var can live at package or function scope.
Without an initial value, numeric types become 0, string "", bool false. This reduces unexpected bugs.
var syntax
var has two forms. First, explicit type: var x int. Second, with value: var x = 10. In the second, Go infers the type from the right side.
You can declare several variables in one line: var a, b int. Even var a, b = 1, 2 with different types is possible.
Package-level var declarations are visible across the file. Inside a function, only that function sees them.
Practice Declare with var
Declare three variables with var: explicit type var ad string = "Ada", inferred from value var yas = 36, and without a value var aktif bool. Print all three with one fmt.Println.
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
func main() {
var ad string = "Ada"
var yas = 36
var aktif bool
fmt.Println(ad, yas, aktif)
}Expected output
Ada 36 false
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the initial value of x in var x int?
- 0 Correct answer
- nil
- 1
- undefined
Explanation: The zero value of int is 0.
2 Variable declaration
To declare an int named x:
____ x intTo declare an int named x:
var x intExplanation: the var keyword declares a variable.
3 Match the declarations
| Term | Meaning |
|---|---|
var x int |
Explicit type |
var x = 5 |
Type inference |
var a, b int |
Multiple |
var x string |
Text |