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Data Types

Introduction

Go is statically typed, meaning variables always have a specific type and that type cannot change.
Data Type for a variable defines:
  • The amount of memory space allocated for variables.
  • A data type specifies the possible values for variables.
  • The operations that can be performed on variables.
Go built-in data types:
  • Numbers
  • Boolean
  • String

Integer

Signed integers

Type
Size
Description (Two's complement)
int8
8 bits
8 bit signed integer
int16
16 bits
16 bit signed integer
int32
32 bits
32 bit signed integer
int64
64 bits
64 bit signed integer,
can also be represented in octal and hexadecimal
int
Platform dependent
signed integers of at least 32-bit in size, not equivalent to int32.

Unsigned integers

Type
Size
Description (Two's complement)
uint8
8 bits
8 bit unsigned integer
uint16
16 bits
16 bit unsigned integer
uint32
32 bits
32 bit unsigned integer
uint64
64 bits
64 bit unsigned integer
uint
Platform dependent
unsigned integers of at least 32-bit in size, not equivalent to int32.
Use int unless for specific reasons for others. Integral types have default value of 0. Octal numbers can be declared using prefix and hexadecimal using the 0x prefix.

Other integer types

Type
Description (Two's complement)
byte
It is alias for and equivalent to uint8
rune
It is alias for and equivalent to int32, used to represent characters.
uintptr
It is used to hold memory address pointers
Golang does not support a char data type, instead it has byte and rune to represent character values. This helps to distinguish characters from integer values. byte data type is represented with a ASCII value and the rune data type is represented with Unicode value encoded in UTF-8 format.
package main
import "fmt"
func main() {
var varByte byte = 'a' // ASCII value of 97
var varRune rune = '♥' // Unicode value of U+2665
fmt.Printf("%c = %d and %c = %U\n", varByte, varByte, varRune, varRune)
}
a = 97 and ♥ = U+2665

Float

Go supports float32 and float64 represented with 32-bit and 64-bit in memory respectively.
var num1 float32 = 20.0320
var num2 = 20.0818 // Type inferred as float64

Complex Numbers

Go supports complex64 and complex128. Each of the type uses float32 and float64 respectively, to represent their real and imaginary parts.
var num1 = 3 + 7i // Type inferred as complex128

​

Boolean

var flag = true

​

String

// No newlines, and can contain escape sequences like \n, \t
var fstr="Hello World"
// Can span multiple lines. Escape characters are not allowed.
var sstr= `Hello world, this
a multi-line text string.`
​

Type Conversions

Syntax: The expression T(v) converts the value v to the type T.

var i int = 42
var f float64 = float64(i)
var u uint = uint(f)
// short syntax
i := 42
f := float64(i) // 42.000000
u := uint(f)
​

Type Inference

When declaring a variable without specifying an explicit type (either by using the := syntax or var = expression syntax), the variable's type is inferred from the value on the right hand side.
package main
​
import "fmt"
​
func main() {
i := 42
f := 12.0212
c := 0.5 + 2i
fmt.Printf("i is of type %T\n", i)
fmt.Printf("f is of type %T\n", f)
fmt.Printf("c is of type %T\n", c)
}
i is of type int
f is of type float64
c is of type complex128
Last modified 2yr ago