go lang 기초

<for>
func superAdd(numbers ...int) int {
	total := 0
	for _, number := range numbers {
		total += number
	}
	return total
}

func main(){
	superAdd(1,2,3,4,5)
}

<if else>
func canIDrink(age int) bool {
	koreanAge := age + 2
	if koreanAge <18 {
		return false
	}
	return ture
}

<array>

func main() {
	names := []string{"nico", "lynn", "dal"}
	names = append(names, "flynn")
	fmt.Println(names)
}

<Maps>

func main() {
	nico := map[string]string{"name":"nico", "age":"12"}
	for key, value := range nico {
		fmt.Println(key, value)
	}
}

<Struct>

type person struct {
	name string
	age int
	favFood []string
}

func main(){
	favFood := []string{"kimchi", "ramen"}
	nico := person{name: "nico", age:18, favFood: favFood}
	fmt.Println(nico.name)
}

<Url Checker>
package main

import (
	"errors"
	"fmt"
	"net/http"
)

var errRequestFailed = errors.New("Request failed")

func main() {
	var results = make(map[string]string)
	urls := []string{
		"https://www.airbnb.com/",
		"https://www.google.com/",
		"https://www.amazon.com/",
		"https://www.reddit.com/",
		"https://www.google.com/",
		"https://soundcloud.com/",
		"https://www.facebook.com/",
		"https://www.instagram.com/",
		"https://academy.nomadcoders.co/",
	}
	for _, url := range urls {
		result := "OK"
		err := hitURL(url)
		if err != nil {
			result = "FAILED"
		}
		results[url] = result
	}
	for url, result := range results {
		fmt.Println(url, result)
	}
}

func hitURL(url string) error {
	fmt.Println("Checking:", url)
	resp, err := http.Get(url)
	if err != nil || resp.StatusCode >= 400 {
		fmt.Println(err, resp.StatusCode)
		return errRequestFailed
	}
	return nil
}

<Go routines>
import (
	"fmt"
	"time"
)

func main() {
	go sexyCount("nico")
	sexyCount("flynn")
}

func sexyCount(person string){
	for i :=0; i < 10; i++{
		fmt.Println(person, "is sexy", i)
		time.Sleep(time.Second)
	}
}

--> go routine은 main function이 돌아가는 동안에만 유효하다. 
--> main function 은 go routine이 완료되길 기다려주지 않는다.

<Channel>
func main(){
	c := make(chan bool)
	people := [2]string{"nico", "flynn"}
	for _, person := range people {
		go isSexy(person, c)
	}
	for i:=0;i<len(people);i++{
		fmt.Println(<-c)
	}

}

func isSexy(person string, c chan bool){
	time.Sleep(time.Seconds * 5)
	c <- true
}

<Url Check with go routine>
package main

import (
	"errors"
	"fmt"
	"net/http"
)

type requestResult struct {
	url    string
	status string
}

var errRequestFailed = errors.New("Request failed")

func main() {
	results := make(map[string]string)
	c := make(chan requestResult)
	urls := []string{
		"https://www.airbnb.com/",
		"https://www.google.com/",
		"https://www.amazon.com/",
		"https://www.reddit.com/",
		"https://www.google.com/",
		"https://soundcloud.com/",
		"https://www.facebook.com/",
		"https://www.instagram.com/",
		"https://academy.nomadcoders.co/",
	}
	for _, url := range urls {
		go hitURL(url, c)
	}

	for i := 0; i < len(urls); i++ {
		result := <-c
		results[result.url] = result.status
	}

	for url, status := range results {
		fmt.Println(url, status)
	}

}

func hitURL(url string, c chan<- requestResult) {
	resp, err := http.Get(url)
	status := "OK"
	if err != nil || resp.StatusCode >= 400 {
		status = "FAILED"
	}
	c <- requestResult{url: url, status: status}
}