> For the complete documentation index, see [llms.txt](https://book.codewithgo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.codewithgo.com/integers.md).

# 12. Integers

### Integer Types

* Integers are used to store natural numbers are 1,2,3.
* Go has 8 types on integers
*  `int8`, `int16`, `int32`, and `int64`, and corresponding unsigned versions `uint8`, `uint16`, `uint32`, and `uint64.`
* unsigned integers can store positive numbers only.
* 8,16,32 and 64 represents how many bits are used to store value.

| Bits | Signed                                                  | Unsigned                        |
| ---- | ------------------------------------------------------- | ------------------------------- |
| 8    | –128 to 127                                             | 0 to 255                        |
| 16   | –32,768 to 32,767                                       | 0 to 65535                      |
| 32   | –2,147,483,648 to 2,147,483,647                         | 0 to 4,294,967,295              |
| 64   | –9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 | 0 to 18,446,744,073,709,551,615 |

### Declaring Integers

Integers are declared using one of the 3 ways:

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

```go
var j int32 = 20
var i int = 10
var i = 10

i := 10
var k int
```

{% endcode %}

If we are not specifying type like in 2nd and 3rd declaration, it will default to `int`

Zero value for integer is `0`

{% hint style="success" %}
Always use short declaration way when assigning initial value. If you wish to initialize a variable to its zero value, use var declaration.
{% endhint %}

### Using Test Driven Development for integers

Learn how to do test driven development when using integers from Chris

{% embed url="<https://github.com/quii/learn-go-with-tests/blob/master/integers.md>" %}