【Go】構造体サンプルメモ

サンプル

package main

import "fmt"

type Person struct {
    name string
    age int
}

func main() {
    // 宣言の後、値を代入
    var person1 Person
    person1.name = "Akira"
    person1.age = 20
    fmt.Println(person1)

    // 宣言＋代入
    person2 := Person{age: 30, name: "Kure"}
    fmt.Println(person2)

    // 宣言＋代入
    person3 := Person{"Aki", 40}
    fmt.Println(person3)
}

package main

import (
    "fmt"
    "encoding/json"
)

func main() {
    type location struct {
        Name string
        Lat float64
        Long float64
    }

    // JSON 変換するためにキーを大文字にしておく必要がある
    locations := []location {
        {Name: "Brandbury Landing", Lat: -4.5895, Long: 137.4417},
        {Name: "Columbia Memorial Station", Lat: -14.56684, Long: 175.472636},
        {Name: "Challenger Memorial Station", Lat: -1.9462, Long: 354.4734},
    }

    // [{Brandbury Landing -4.5895 137.4417} {Columbia Memorial Station -14.56684 175.472636} {Challenger Memorial Station -1.9462 354.4734}]
    fmt.Println(locations)

    b, _ := json.Marshal(locations)
    // [{"Name":"Brandbury Landing","Lat":-4.5895,"Long":137.4417},{"Name":"Columbia Memorial Station","Lat":-14.56684,"Long":175.472636},{"Name":"Challenger Memorial Station","Lat":-1.9462,"Long":354.4734}]
    fmt.Println(string(b))

    // JSONキーを指定
    type location2 struct {
        Name string `json:"name"`
        Lat float64 `json:"lat"`
        Long float64 `json:"long"`
    }

    locations2 := []location2 {
        {Name: "Brandbury Landing", Lat: -4.5895, Long: 137.4417},
        {Name: "Columbia Memorial Station", Lat: -14.56684, Long: 175.472636},
        {Name: "Challenger Memorial Station", Lat: -1.9462, Long: 354.4734},
    }

    // [{Brandbury Landing -4.5895 137.4417} {Columbia Memorial Station -14.56684 175.472636} {Challenger Memorial Station -1.9462 354.4734}]
    fmt.Println(locations2)

    c, _ := json.MarshalIndent(locations2, "", "  ")
  //    [
  //  {
  //    "name": "Brandbury Landing",
  //    "lat": -4.5895,
  //    "long": 137.4417
  //  },
  //  {
  //    "name": "Columbia Memorial Station",
  //    "lat": -14.56684,
  //    "long": 175.472636
  //  },
  //  {
  //    "name": "Challenger Memorial Station",
  //    "lat": -1.9462,
  //    "long": 354.4734
  //  }
  //]
    fmt.Println(string(c))
}

参考

改訂2版 基礎からわかる Go言語

posted with amazlet at 20.02.15

古川 昇
シーアンドアール研究所 (2015-07-17)
売り上げランキング: 201,077

Amazon.co.jpで詳細を見る