Data Types

Anonymous contributor's avatar
Anonymous contributor
Anonymous contributor's avatar
Anonymous contributor
Published Nov 2, 2021Updated Nov 8, 2021
Contribute to Docs

Data types are the classifications given to the different kinds of values used in everyday programming. In Go, there are seven fundamental data types: Numbers, Strings, Booleans, Arrays, Structs, Slices, and Pointers.


In Go, any number is regarded as number, but there are three sub-categories:

  • Integers (signed and unsigned)
  • Floating-point numbers
  • Complex numbers


Integers are number-types that are either:

  • Signed (int) integers that can be positive or negative.
  • Unsigned (uint) integers ranging from 0 to positive infinity.

Each integer value comes in 4 different memory sizes.

  • 8-bit: int8/uint8
  • 16-bit: int16/uint16
  • 32-bit: int32/uint32
  • 64-bit: int64/uint64
  • 32- or 64-bit based on system architecture: int/uint
  • Synonym for int32: rune
  • synonym for int8: byte

Floating-Point Numbers

Floating-point numbers can contain a decimal point. There are two different sizes.

  • 32-bit: float32
  • 64-bit: float64

Complex Numbers

Complex numbers are composed of a real number and an imaginary number. The real number is either a float. There are two different sizes:

  • 32-bit float + imaginary number: complex64
  • 64-bit float + imaginary number: complex128
// Initialize with complex() taking 2 arguments: a float and a complex number
var complex complex64 = complex(1, 2) // Equals 1 + 2i

Variables can also be initialized with a shorthand:

complex := 1 + 2i


A string represents a sequence of characters. Strings are immutable; once they are created they can’t be modified.

var s string
s = "Hello, World!"


A boolean can hold one of two possible values, either true or false.

var isValid bool
isValid = true
isValid = false


Arrays are list with static capacity. They can’t change their capacity after the declaration.

// Declare and initialize an arraz of capacity 5 and fill it with elements
someArray := [5]int{0, 2, 3, 4, 5}


Slices can change their capacity dynamically even after their declaration. Under the hood a slice references an array. If the array changes, so does the slice.

// Copy the elements from index 0 until (excluding) index 3 into a slace
var slice []int = someArary[0:3]


In Go, a struct is a more complex type that can contain custom fields. It’s similar to an object in JavaScript or a dictionary in Python. The fields of a struct can be accessed with a dot ..

// Declaration with "type ... struct" keywords
type Box struct {
X int
Y int

Structs are initialized by:

  1. Referencing the name of the struct
  2. Passing zero, any or all of the fields of the struct.

The fields without a value will be initialized with zero-values by default.

// Initialization
b := Box{1, 2}


Pointers contain the memory address of the variable they are based on. Pointers used *.

// Declaration of a pointer with *
var p *int
someInteger := 42
// Create pointer from variable using "&"
p = &someInteger

All contributors

Looking to contribute?

Learn Go on Codecademy