[Go Tutorials P3] Variable Declaration

Go is a statically typed, complied language known for its simplicity and efficiency. One of the first things every Go developer learns is how to declare variables-whether to store a simple number, a string, or more complex data.

1. Short Variable Declaration(:=)

This is the most concise way to declare variables in Go. It's used within functions and allows Go to infer the variables's type based on the assigned value.

name := "Gopher"
age := 10

⚠️ You cannot use := outside of functions.

2. Explicit Declaration with var

The var keyword is the traditional way to declare variables. It's useful when:

• You want to specify the variables's type
• You're declaring a variable outside of a function

var name string = "Gopher"
var age int
age = 25

This form is more verbose, but it's clearer when types matter.

3. Type Inference with var

If you want Go to infer the type but still want to use var (example for package-level declarations), you can omit the type:

var isReady = true

Go will automatically assign bool to isReady based on the true value.

4. Grouped Variable Declaration

When you need to declare multiple related variables, Go allows you to group them using parentheses:

var (
    name  string = "Gopher"
    age   int    = 10
    score float64
)

This keeps your code tidy, especially in packages or structs.

5. Constants with const

Use const to declare values that should never change. Go requires constants to be assigned at the time of declaration.

const Pi = 3.14
const Greeting = "Hello, Go!"

6. Zero Values in Go

If a variable is declared without an intial value, Go assigns a zero value based on its type:

var n int         // 0
var s string    // ""
var n bool      // false

This behavior ensures your code doesn't break due ti uninitialized variables.

7. Best Practices

• Use := for local, short-lived variables
• Use var when declaring variable outside of functions or when explicit typing is necessary.
• Group related variables together for readability
• Use const for fixed values