Challenge 1 — Solution

Task: Define a struct Product with fields Name (string), Price
(float64), and InStock (bool), with json tags using lowercase key
names. Create one, marshal it with json.Marshal, and print the
resulting JSON string.

package main

import (
	"encoding/json"
	"fmt"
)

type Product struct {
	Name    string  `json:"name"`
	Price   float64 `json:"price"`
	InStock bool    `json:"inStock"`
}

func main() {
	product := Product{Name: "Keyboard", Price: 49.99, InStock: true}

	data, err := json.Marshal(product)
	if err != nil {
		fmt.Println("Error:", err)
		return
	}

	fmt.Println(string(data))
}


Expected output:

{"name":"Keyboard","price":49.99,"inStock":true}

Notes:
- Without the json tags, the output would use the capitalised Go
  field names instead (Name, Price, InStock) — the tags are what
  produce the lowercase keys typically expected by JSON APIs.
- json.Marshal returns []byte, not a string — string(data) converts
  the raw bytes into something printable.
- The field order in the output JSON matches the struct's field
  declaration order, not alphabetical order.