Basic Types

Strings

s1 := "Hello" + "World"

s2 := `A "raw" string literal
can include line breaks.`

// Outputs: 10
fmt.Println(len(s1))

// Outputs: Hello
fmt.Println(string(s1[0:5]))

Strings are of type string.

Numbers

num := 3         // int
num := 3.        // float64
num := 3 + 4i    // complex128
num := byte('a') // byte (alias: uint8)

var u uint = 7        // uint (unsigned)
var p float32 = 22.7  // 32-bit float

Operators

x := 5
x++
fmt.Println("x + 4 =", x + 4)
fmt.Println("x * 4 =", x * 4)

Booleans

isTrue   := true
isFalse  := false

Operators

fmt.Println(true && true)   // true
fmt.Println(true && false)  // false
fmt.Println(true || true)   // true
fmt.Println(true || false)  // true
fmt.Println(!true)          // false

Arrays

┌────┬────┬────┬────┬─────┬─────┐
| 2  | 3  | 5  | 7  | 11  | 13  |
└────┴────┴────┴────┴─────┴─────┘
  0    1    2    3     4     5

---

primes := [...]int{2, 3, 5, 7, 11, 13}
fmt.Println(len(primes)) // => 6

// Outputs: [2 3 5 7 11 13]
fmt.Println(primes)

// Same as [:3], Outputs: [2 3 5]
fmt.Println(primes[0:3])

---

var a [2]string
a[0] = "Hello"
a[1] = "World"

fmt.Println(a[0], a[1]) //=> Hello World
fmt.Println(a)   // => [Hello World]

2d array

var twoDimension [2][3]int
for i := 0; i < 2; i++ {
    for j := 0; j < 3; j++ {
        twoDimension[i][j] = i + j
    }
}
// => 2d:  [[0 1 2] [1 2 3]]
fmt.Println("2d: ", twoDimension)

Pointers

func main () {
  b := *getPointer()
  fmt.Println("Value is", b)
}

func getPointer () (myPointer *int) {
  a := 234
  return &a
}

a := new(int)
*a = 234

See: Pointers

Slices

s := make([]string, 3)
s[0] = "a"
s[1] = "b"
s = append(s, "d")
s = append(s, "e", "f")

fmt.Println(s)
fmt.Println(s[1])
fmt.Println(len(s))
fmt.Println(s[1:3])

slice := []int{2, 3, 4}

See also: Slices example

Constants

const s string = "constant"
const Phi = 1.618
const n = 500000000
const d = 3e20 / n
fmt.Println(d)

Type conversions

i := 90
f := float64(i)
u := uint(i)

// Will be equal to the character Z
s := string(i)

How to get int string?

i := 90

// need import "strconv"
s := strconv.Itoa(i)
fmt.Println(s) // Outputs: 90

Comments