Go Variables

Links: - 103 Golang Index
- Go - Basics

Variables in GO¶

Variables belong to runtime
- Example: x,y := 6,0; fmt.Printf(x/y) - This will throw run time error.
In GO all variables are initialised. So even if you don't initialise the declared variables they will get a default type. Example: var value int; fmt.Println(value) - 0
- integer = 0
- float = 0.0
- bool = false
- string = "" (empty string)
- pointer = nil
Multiple statements can be separated in Go using ;
There are 2 ways of declaring variables in Go.
- var keyword:
  - Syntax: var var_name type - var test string
  - var age int = 10 - type can be omitted as it can be inferred by Go during compile time hence we can omit int here.
  - var name = "test"
- walrus operator (:=): declaring and initialising
  - s := "hello"
  - Cannot be used for already defined variables
  - Walrus operator only works in block scope. Can't be used at package scope (outside main or any other function)

Type of a variable cannot be changed once declared.

Unused variables generate compile time errors.

This can be solved by using _ which is used to mute the compiler. It is always used on the left hand side. var name = "test"; _ = name

Use var or walrus operator if you want to create variables. If you want to change the value of variables then use =. name = "hello" where name has been created.

You cannot redeclare variables in a block.

Multiple variable declaration: car, price := "audi", 3900
- Cannot be used to redefine variables unless one of the variables is new
  - car, price := "audi",399; car, price := "test", 343 - this would give an error
  - car, price := "audi", 455; car, new_var := "test", true - this is fine
    - The second statement is equivalent to car = "test";var new_var = true

Multiple declaration using var

The below syntax is good for readability

// elaborate way
var (
    name string
    age int
    salary float64
)

// we can also initialise them
var (
    a int = 45
    b string = "hello"
)

We use multiple variable declaration using walrus operator when we know the value of variables otherwise we use the var.

Last updated: 2022-05-28