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Initializer list

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一般的なトピック
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General topics
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フロー制御
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Flow control
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条件付き実行文
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Conditional execution statements
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繰り返し文
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Iteration statements
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文をジャンプします
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Jump statements
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機能します
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Functions
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関数の宣言
ラムダ関数の宣言
関数テンプレート
の歴史。インライン指定
例外仕様 (廃止予定)
noexcept指定子 (C++11)
例外
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Exceptions
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名前空間
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Namespaces
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タイプ
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Types
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decltype specifier (C++11)
指定子
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Specifiers
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CV指定
貯蔵期間指定
constexprの指定子 (C++11)
自動指定 (C++11)
alignas指定子 (C++11)
初期化
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Initialization
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リテラル
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Literals
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Expressions
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代替表現
ユーティリティ
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Utilities
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タイプ
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Types
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typedef declaration
型の別名宣言 (C++11)
属性 (C++11)
キャストします
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Casts
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暗黙の型変換
const_cast conversion
static_cast conversion
dynamic_cast conversion
reinterpret_cast conversion
Cスタイルキャストと機能
メモリの割り当て
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Memory allocation
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クラス
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Classes
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友人指定子
初期化リスト
クラス固有の機能特性
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Class-specific function properties
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明示 (C++11)
静的
特殊なメンバ関数
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Special member functions
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テンプレート
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Templates
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クラステンプレート
関数テンプレート
テンプレートの特殊化
パラメーターパック (C++11)
その他
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Miscellaneous
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インラインアセンブリ
 
はstd :: initializer_listと混同しないでください)​​
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( Not to be confused with はstd :: initializer_list )
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彼らは、メンバーと祖先の初期化のために責任があるコンストラクタの一部です
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They are the part of a constructor which is responsible for member and ancestor initialization
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[編集] 構文

constructor_signature : member_constructor_calls { constructor_body }

[編集] 説明

初期化子リストは、オブジェクトの初期化が必要な箇所ですが、基底クラスやメンバのコンストラクタが呼び出されている場所がある.
Original:
The initializer list is the place where initialization of the object should occur, there is where the constructors for base classes and members are called.
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宣言されているようなメンバーは、彼らは初期化子リストで表示されないように、同じ順序で初期化され.
Original:
Members are initialized in the same order as they are declared, not as they appear in the initializer list.
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コンストラクタのパラメータは、メンバーの一人、intializerリスト内部のコンストラクタ呼び出しで渡されて、その識別子の曖昧さと同じ名前を持つ場合は、このパラメータを(メンバーではありません)を選択する解決されています.
Original:
If a parameter in the constructor has the same name as one of the members, the ambiguity of that identifier being passed in a constructor call inside the intializer list is resolved choosing the parameter (and not the member).
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リスト内に存在しないメンバや基本クラスは、デフォルトで構成されるでしょう
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Members or base classes not present in the list will be default constructed
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[編集]

struct Class : public Base
{
    int x;
    int y;
 
    Class ( int x )
      : Base ( 123 ), // initialize base class
        x ( x ),      // x (member) is initialized with x (parameter)
        y ( 0 )       // y initialized to 0
    {}                // empty constructor body
 
    Class ( double a )
      : y ( a+1 ),
        x ( y ) // x will be initialized before y, this means that its value here is undefined
    {}          // No base class constructor in list, this is the same as calling Base()
 
    Class()
    try
      : Base ( 789 ),
        x ( 0 ),
        y ( 0 )
    {
        // no exception
    }
    catch (...)
    {
        // exception occurred on initialization
    }
};