# 10. Variables

### What are Variables?

Variables are named memory locations, that are used to refer to data in our program. General format for variable is Go is: `var name type = expression`

Variable names must start with letter and can contain letter and number.

### Declaring variables

Variables are declared using `var`keyword. Before using variables, they need to be declared. For declaring variables:

* Use the var keyword. 
* Write a variable name. 
* Write the variable type. 
* Optionally, assign value using equals `=`

{% code title="main.go" %}

```go
func main() {
	var s string
	s = "sumit"
	var i, j, k int
}
```

{% endcode %}

Multiple variables of same type can be declared using comma separation in name. All declared variables should be used.Variable name can not be reserved keywords.

{% code title="keywords" %}

```go
break        default      func         
interface    select       case         
defer        go           map          
struct       chan         else         
goto         package      switch
const        fallthrough  if           
range        type         continue     
for          import       return       
var
```

{% endcode %}

### Short variable declaration

Short variable declaration may be used to declare and initialize local variables.It takes the form `name` `:=` `expression.`Below declarations are one and the same

{% code title="main.go" %}

```go
func main() {
	var s string
	s = "hello, world!"
	t := "hello, world!"

	var i int
	i = 42
	j := 42
}
```

{% endcode %}

### Variable Scope

Variables are visible only with the scope they are declared. We can access the variable so long as it’s in scope, but once a variable is no longer in scope, attempts to access it will report an error. Scope is defined by braces `{}`

### From the Docs

{% embed url="<https://golang.org/doc/effective_go.html#variables>" %}
Effective Go
{% endembed %}


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