hello-world-16.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os"
	"regexp"
)

func regexpDemo() {
	// 直接匹配
	match, _ := regexp.MatchString("p([a-z]+)ch", "peach")
	fmt.Println(match)

	r, _ := regexp.Compile("p([a-z]+)ch")
	fmt.Println(r.MatchString("peach"))

	fmt.Println(r.FindString("peach punch"))
	fmt.Println(r.FindStringIndex("peach punch"))

	fmt.Println(r.FindStringSubmatch("peach punch"))
	fmt.Println(r.FindStringSubmatchIndex("peach punch"))

	fmt.Println(r.FindAllString("peach punch pinch", -1))
	fmt.Println(r.FindAllStringSubmatchIndex("peach punch pinch", -1))
	fmt.Println(r.FindAllString("peach punch pinch", 2))

	fmt.Println(r.Match([]byte("peach")))

	r = regexp.MustCompile("p([a-z]+)ch")
	fmt.Println(r)

	fmt.Println(r.ReplaceAllString("a peach", "<fruit>"))

	in := []byte("a peach")
	out := r.ReplaceAllFunc(in, bytes.ToUpper)
	fmt.Println(string(out))
}

type response1 struct {
	Page   int
	Fruits []string
}

type response2 struct {
	Page   int      `json:"page"`
	Fruits []string `json:"fruits"`
}

func jsonDemo() {
	bolB, _ := json.Marshal(true)
	fmt.Println(string(bolB))

	intB, _ := json.Marshal(1)
	fmt.Println(string(intB))

	fltB, _ := json.Marshal(2.34)
	fmt.Println(string(fltB))

	strB, _ := json.Marshal("gopher")
	fmt.Println(string(strB))

	slcD := []string{"apple", "peach", "pear"}
	slcB, _ := json.Marshal(slcD)
	fmt.Println(string(slcB))

	mapD := map[string]int{"apple": 5, "lettuce": 7}
	mapB, _ := json.Marshal(mapD)
	fmt.Println(string(mapB))

	res1D := &response1{
		Page:   1,
		Fruits: []string{"apple", "peach", "pear"}}
	res1B, _ := json.Marshal(res1D)
	fmt.Println(string(res1B))

	res2D := &response2{
		Page:   1,
		Fruits: []string{"apple", "peach", "pear"}}
	res2B, _ := json.Marshal(res2D)
	fmt.Println(string(res2B))

	byt := []byte(`{"num":6.13,"strs":["a","b"]}`)

	// 键为 string，值为任意值的 map。
	var dat map[string]interface{}

	if err := json.Unmarshal(byt, &dat); err != nil {
		panic(err)
	}
	fmt.Println(dat)

	num := dat["num"].(float64)
	fmt.Println(num)

	strs := dat["strs"].([]interface{})
	str1 := strs[0].(string)
	fmt.Println(str1)

	str := `{"page": 1, "fruits": ["apple", "peach"]}`
	res := response2{}
	json.Unmarshal([]byte(str), &res)
	fmt.Println(res)
	fmt.Println(res.Fruits[0])

	enc := json.NewEncoder(os.Stdout)
	d := map[string]int{"apple": 5, "lettuce": 7}
	enc.Encode(d)
}