Go Install
~$ sudo apt-get update
~$ sudo apt install golang-go
~$ go version
go version go1.18.1
Hugo Install
~$ sudo apt update
~$ sudo apt -y install hugo
~$ hugo version
hugo v0.92.2
Hello World
サンプルプログラム
package main
import "fmt"
func main() {
message := greetMe("world")
fmt.Println(message)
}
func greetMe(name string) string {
return "Hello, " + name + "!"
}
Run the program as below:
$ go run hello.go
GO Variables
Normal Declaration:
var msg string
msg = "Hello"
Shortcut:
msg := "Hello"
Constants
const Phi = 1.618
GO Condition
if day == "sunday" || day == "saturday" {
rest()
} else if day == "monday" && isTired() {
groan()
} else {
work()
}
if _, err := doThing(); err != nil {
fmt.Println("Uh oh")
GO Switch
switch day {
case "sunday":
// cases don't "fall through" by default!
fallthrough
case "saturday":
rest()
default:
work()
}
GO Loop
for count := 0; count <= 10; count++ {
fmt.Println("My counter is at", count)
}
entry := []string{"Misaki","Taro","Hanako"}
for i, val := range entry {
fmt.Printf("At position %d, the character %s is present\n", i, val)
n := 0
x := 42
for n != x {
n := guess()
}
GO Strings
str := "Hello"
Multiline string
str := `Multiline
string`
GO Numbers
Typical types
num := 3 // int
num := 3. // float64
num := 3 + 4i // complex128
num := byte('a') // byte (alias for uint8)
Other Types
var u uint = 7 // uint (unsigned)
var p float32 = 22.7 // 32-bit float
GO Arrays
// var numbers [5]int
numbers := [...]int{0, 0, 0, 0, 0}
Pointers
func main () {
b := *getPointer()
fmt.Println("Value is", b)
func getPointer () (myPointer *int) {
a := 234
return &a
a := new(int)
*a = 234
Pointers point to a memory location of a variable. Go is fully garbage-collected.
GO Type Conversion
i := 2
f := float64(i)
u := uint(i)
GO Slice
slice := []int{2, 3, 4}
slice := []byte("Hello")
GO Condition
if day == "sunday" || day == "saturday" {
rest()
} else if day == "monday" && isTired() {
groan()
} else {
work()
}
if _, err := doThing(); err != nil {
fmt.Println("う～ん！")