golang

hello world

package main

import "fmt"

func main () {
  fmt.Println("Hello World!")
}

variables

• var a, b type = initial_a, initial_b
• a := initial_a (no var, can only in function)
• zero values // if value is not initialed the value will be zero value.
• const a = 111

For loop

• while: for i < n
• c-style: for i := 0; i < n; i++ {
• infinite-loop: for {
• range iterate: for i/k, v := range array/map {

If/Else

• no ternary: if i < 0 { a = 100 } else {a = 101}

Switch/Case

Array

• golang array has length in it's type
• var a [n]type
• literal value: [n]type{a, b, c}

Slice

• array without length
• make([]type, init_size)
• slice = append(slice, value)
• slice operator: slice[low:]

Map

• make(map[key-type]val-type)
• n := map[string]int{"foo": 1, "bar": 2}

Function

• func funcname (a type) returntype
• multiple return type: func div (a double, b double) (int, error)
• named return type

Pointer

• pointer type: *type
• dereference: *pointer_variable
• variable to pointer: &variable

Struct

• type sname struct {
• struct method: fun (r receiver_type) (a int) return_type
  • values and pointers method are handled automatically in golang

Interface

• type iface interface {
• empty interface: interface {}
  • any value match empty interface

Error

Goroutine/Channel

• start a goroutine: go fun()
• make(chan string, buffer? int)
• channel directions:
  • send: chan <- message
  • receive: message := <- chan
• select: wait multiple channel
  • timeout
  • non-blocking
• close channel
  • range over channel