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+ < span itemprop ="name "> リファレンス</ span >
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+ < a href ="../../../reference/flat_map/flat_map.html " itemprop ="url ">
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+ < span itemprop ="name "> flat_map</ span >
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+ </ a >
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+ </ span >
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+ < li class ="active " itemscope itemtype ="http://www.schema.org/SiteNavigationElement ">
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+ < span >
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+
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+ < span itemprop ="name "> keys</ span >
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+ < p class ="text-right "> < small >
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+ 最終更新日時(UTC):
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+ < span itemprop ="datePublished " content ="2025-01-27T14:35:27 ">
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+ 2025年01月27日 14時35分27秒
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+ </ span >
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+ < span itemprop ="author " itemscope itemtype ="http://schema.org/Person ">
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+ が更新
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+ < a class ="history " target ="_blank " href ="https://github.com/cpprefjp/site/commits/master/reference/flat_map/flat_map/keys.md ">
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+ < span class ="fa fa-fw fa-clock-o fa-flip-horizontal "> </ span > 履歴
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+ </ a >
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+ < a class ="edit " target ="_blank " href ="https://github.com/cpprefjp/site/edit/master/reference/flat_map/flat_map/keys.md ">
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+ < span class ="fa fa-fw fa-pencil "> </ span > 編集
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+ </ div >
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+ < div class ="row ">
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+ < div class ="col-sm-12 content-body ">
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+
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+ < div class ="identifier-type "> function</ div > < div class ="header "> <flat_map></ div > < h1 itemprop ="name "> < span class ="namespace " title ="namespace std "> std::</ span > < span class ="class " title ="class flat_map "> flat_map::</ span > < span class ="token "> keys</ span > < span class ="cpp cpp23 " title ="C++23で追加 "> (C++23)</ span > </ h1 >
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+ < div itemprop ="articleBody "> < p > < div class ="codehilite "> < pre > < span > </ span > < code > < span class ="k "> const</ span > < span class ="n "> key_container_type</ span > < span class ="o "> &</ span > < span class ="n "> keys</ span > < span class ="p "> ()</ span > < span class ="k "> const</ span > < span class ="k "> noexcept</ span > < span class ="p "> ;</ span > < span class ="c1 "> // C++23</ span >
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+ </ code > </ pre > </ div >
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+ </ p >
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+ < h2 > 概要</ h2 >
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+ < p > キーのコンテナを取得する。</ p >
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+ < h2 > < a class ="cpprefjp-defined-word " data-desc ="関数呼び出し式の評価結果となるオブジェクト・値 "> 戻り値</ a > </ h2 >
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+ < p > < code > flat_map</ code > クラス内部で保持しているキーのコンテナ。</ p >
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+ < h2 > < a class ="cpprefjp-defined-word " data-desc ="関数等の意味論を構成する要素の1つ。Complexity。関数が使うアルゴリズムの空間計算量・時間計算量 "> 計算量</ a > </ h2 >
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+ < p > 定数時間</ p >
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+ < h2 > 例</ h2 >
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+ < p > < div class ="yata " id ="2a19951c37d035d451521ac22ca5ec30f0b4ac32 "> < div class ="codehilite "> < pre > < span > </ span > < code > < span class ="cp "> #include</ span > < span class ="cpf "> < a href ="../../flat_map.html "> <flat_map></ a > </ span > < span class ="cp "> </ span >
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+ < span class ="cp "> #include</ span > < span class ="cpf "> < a href ="../../iostream.html "> <iostream></ a > </ span > < span class ="cp "> </ span >
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+ < span class ="cp "> #include</ span > < span class ="cpf "> < a href ="../../type_traits.html "> <type_traits></ a > </ span > < span class ="cp "> </ span >
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+ < span class ="cp "> #include</ span > < span class ="cpf "> < a href ="../../vector.html "> <vector></ a > </ span > < span class ="cp "> </ span >
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+
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+ < span class ="kt "> int</ span > < span class ="nf "> main</ span > < span class ="p "> ()</ span >
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+ < span class ="p "> {</ span >
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+ < span class ="n "> std</ span > < span class ="o "> ::</ span > < span class ="n "> flat_map</ span > < span class ="o "> <</ span > < span class ="kt "> int</ span > < span class ="p "> ,</ span > < span class ="kt "> char</ span > < span class ="o "> ></ span > < span class ="n "> fm</ span > < span class ="p "> ;</ span >
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+ < span class ="n "> fm</ span > < span class ="p "> [</ span > < span class ="mi "> 3</ span > < span class ="p "> ]</ span > < span class ="o "> =</ span > < span class ="sc "> 'C'</ span > < span class ="p "> ;</ span >
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+ < span class ="n "> fm</ span > < span class ="p "> [</ span > < span class ="mi "> 1</ span > < span class ="p "> ]</ span > < span class ="o "> =</ span > < span class ="sc "> 'A'</ span > < span class ="p "> ;</ span >
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+ < span class ="n "> fm</ span > < span class ="p "> [</ span > < span class ="mi "> 2</ span > < span class ="p "> ]</ span > < span class ="o "> =</ span > < span class ="sc "> 'B'</ span > < span class ="p "> ;</ span >
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+
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+ < span class ="k "> static_assert</ span > < span class ="p "> (</ span > < span class ="n "> < a href ="../../type_traits/is_same.html "> std::is_same_v</ a > </ span > < span class ="o "> <</ span > < span class ="k "> decltype</ span > < span class ="p "> (</ span > < span class ="n "> fm</ span > < span class ="p "> .</ span > < span class ="n "> < span style ="color:#ff0000 "> keys()</ span > </ span > < span class ="p "> ),</ span > < span class ="k "> const</ span > < span class ="n "> < a href ="../../vector/vector.html "> std::vector</ a > </ span > < span class ="o "> <</ span > < span class ="kt "> int</ span > < span class ="o "> >&></ span > < span class ="p "> );</ span >
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+
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+ < span class ="k "> for</ span > < span class ="p "> (</ span > < span class ="k "> auto</ span > < span class ="nl "> i</ span > < span class ="p "> :</ span > < span class ="n "> fm</ span > < span class ="p "> .</ span > < span class ="n "> < span style ="color:#ff0000 "> keys()</ span > </ span > < span class ="p "> )</ span > < span class ="p "> {</ span >
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+ < span class ="n "> < a href ="../../iostream/cout.html "> std::cout</ a > </ span > < span class ="o "> <<</ span > < span class ="n "> i</ span > < span class ="o "> <<</ span > < span class ="n "> < a href ="../../ostream/endl.html "> std::endl</ a > </ span > < span class ="p "> ;</ span >
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+ < span class ="p "> }</ span >
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+ < span class ="p "> }</ span >
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+ </ code > </ pre > </ div >
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+ </ div > </ p >
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+ < h3 > 出力</ h3 >
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+ < p > < pre > < code > 1
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+ 2
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+ 3
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+ </ code > </ pre > </ p >
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+ < h2 > バージョン</ h2 >
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+ < h3 > 言語</ h3 >
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+ < ul >
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+ < li > C++23</ li >
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+ </ ul >
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+ < h3 > 処理系</ h3 >
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+ < ul >
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+ < li > < a href ="../../../implementation.html#clang "> Clang</ a > : ??</ li >
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+ < li > < a href ="../../../implementation.html#gcc "> GCC</ a > : ??</ li >
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+ < li > < a href ="../../../implementation.html#visual_cpp "> Visual C++</ a > : ??</ li >
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+ </ ul >
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+ < h2 > 関連項目</ h2 >
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+ < table border ="1 " bordercolor ="#888 " style ="border-collapse:collapse ">
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+ < thead >
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+ < tr >
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+ < th > 名前</ th >
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+ < th > 説明</ th >
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+ </ tr >
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+ </ thead >
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+ < tbody >
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+ < tr >
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+ < td > < code > < a href ="values.html "> flat_map::values</ a > </ code > </ td >
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+ < td > 値のコンテナを取得する</ td >
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+ </ tr >
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+ </ tbody >
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+ </ table > </ div >
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