Golang学习

Hello World

package main

import "fmt"

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

Variables assignment

1 2	var age int age = 20

1 2	// recommanded age := 20

1 2	// unpack, like python. name, age := "Bob", 20

Constants define

1	const Distance = 1000

Basic types

strings
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s0 := "string"
s1 := `mutiple
strings`

numbers

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3

i := 100  //int
f := 1.0  //float64
b := byte('a') //byte

array

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3

// The size of array is fixed.
arr := [5]string{"a", "b", "c", "d", "e"}
arrAuto := [...]int{1, 2, 3, 4, 5, 6}

slice

1 2	// slice has a dynamic size, unlike array. slice := []int{9, 10, 100, 73}

map

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// type of key is string
// type of value is nil slice
dict := map[string][]string{}

Flow control

conditional

if myAppearance == "handsome" && myMoney == "countless" {
  doAnythingIWanna()
}else if myMoney == "good" {
  sleepAndEatAnytime()
}else {
  code()
}

statement in if

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if res, err := getResult(); err != nil {
  doRightThing()
}

switch

switch sex {
  case "male": 
    fmt.Println("hi, man")
  case "female":
    fmt.Println("hi, women")
  default:
    fmt.Println("excuse me, who are you?")
}

for range loop

slice := []string{"h", "e", "l", "l", "o"}
for index, item := range slice {
  fmt.Printf("%d====>>%s", index, item)
}

for loop

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for i := 0; i <= 10; i++ {
  fmt.Println(i)
}

Function

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func sum(x, y int) int {
  return x + y
}

func flow(file *fileType) {
  // outside variable will be changed
  change(file)
}