golang一些常用库(1)

goCopy codepackage main

import "fmt"

func main() {
    name := "Gopher"
    age := 3
    fmt.Printf("Hello, %s! You are %d years old.\n", name, age)
}

goCopy codepackage main

import (
	"fmt"
	"net/http"
)

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

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

goCopy codepackage main

import (
	"fmt"
	"os"
)

func main() {
	args := os.Args
	fmt.Println("Command-line arguments:", args)
	
	hostname, err := os.Hostname()
	if err == nil {
		fmt.Println("Hostname:", hostname)
	}
}

goCopy codepackage main

import (
	"fmt"
	"time"
)

func main() {
	now := time.Now()
	fmt.Println("Current time:", now.Format("2006-01-02 15:04:05"))

	oneHourLater := now.Add(time.Hour)
	fmt.Println("One hour later:", oneHourLater.Format("15:04:05"))
}

goCopy codepackage main

import (
	"encoding/json"
	"fmt"
)

type Person struct {
	Name string `json:"name"`
	Age  int    `json:"age"`
}

func main() {
	p := Person{"Alice", 25}
	jsonData, err := json.Marshal(p)
	if err == nil {
		fmt.Println("JSON data:", string(jsonData))
	}

	// 反序列化
	var newPerson Person
	err = json.Unmarshal(jsonData, &newPerson)
	if err == nil {
		fmt.Println("Decoded person:", newPerson)
	}
}

goCopy codepackage main

import (
	"crypto/md5"
	"encoding/hex"
	"fmt"
)

func main() {
	data := []byte("Hello, Golang!")
	hash := md5.Sum(data)
	md5String := hex.EncodeToString(hash[:])
	fmt.Println("MD5 hash:", md5String)
}

goCopy codepackage main

import (
	"fmt"
	"strconv"
)

func main() {
	str := "42"
	num, err := strconv.Atoi(str)
	if err == nil {
		fmt.Println("Converted number:", num)
	}

	// 整数转字符串
	newStr := strconv.Itoa(123)
	fmt.Println("Converted string:", newStr)
}