struct.go

package main

import (
	"encoding/json"
	"fmt"
)

type Profile struct {
	Name   string  `json:"name"`
	Age    int     `json:"age"`
	Height float64 `json:"height"`
}

func main() {
	prof := Profile{
		Name:   "Yamada Tarou",
		Age:    18,
		Height: 178.5,
	}

	profJson, _ := json.Marshal(prof)
	fmt.Println(string(profJson))
}