한 기사에서 읽어보세요: Go 언어로 마스터해야 하는 클래스 라이브러리는 무엇입니까?

package main

import "fmt"

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

package main

import (
    "os"
    "fmt"
)

func main() {
    file, err := os.Create("test.txt")
    if err != nil {
        fmt.Println(err)
        return
    }

    defer file.Close()
    file.WriteString("Hello, File!")
}

package main

import (
    "net/http"
    "fmt"
)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, HTTP!")
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

package main

import (
    "database/sql"
    _ "github.com/go-sql-driver/mysql"
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(localhost:3306)/dbname")
    if err != nil {
        println(err)
        return
    }

    defer db.Close()
}

package main

import (
    "sync"
    "fmt"
)

func main() {
    var wg sync.WaitGroup
    wg.Add(1)

    go func() {
        defer wg.Done()
        fmt.Println("Hello, Concurrency!")
    }()

    wg.Wait()
}