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Go言語: マップのキーが存在するかチェックしたい

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Go言語でマップにキーが定義されているのかを調べる方法です。マップのキーを参照すると、値と存在有無のbool値が戻り値になります。このbool値を確認することで、キーの有無が分かります。

package main

import "fmt"

func main() {
    dict := map[string]int{
        "foo": 1,
    }

    if val, ok := dict["foo"]; ok {
        fmt.Printf("foo exists. The value is %#v", val)
    }
}

このコードを実行してみる

suin
Qiita 4位/TypeScript入門書執筆中/TypeScripterのための座談会「YYTypeScript」主催/『実践ドメイン駆動設計』書籍邦訳レビュア/分報Slack考案/YYPHP主催/CodeIQマガジン執筆/株式会社クラフトマンソフトウェア創設/Web自動テスト「ShouldBee」の開発/TypeScript/DDD/OOP
https://yyts.connpass.com/
shouldbee
開発者向けテスト支援サービスShouldBeeを開発・運営するスタートアップ(onlab第8期)
http://shouldbee.at
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