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200+
201+ < p class ="text-right "> < small >
202+ 最終更新日時(UTC):
203+ < span itemprop ="datePublished " content ="2025-01-26T08:31:30 ">
204+ 2025年01月26日 08時31分30秒
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210+ が更新
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216+ < span class ="fa fa-fw fa-clock-o fa-flip-horizontal "> </ span > 履歴
217+ </ a >
218+ < a class ="edit " target ="_blank " href ="https://github.com/cpprefjp/site/edit/master/reference/flat_map/flat_map/key_comp.md ">
219+ < span class ="fa fa-fw fa-pencil "> </ span > 編集
220+ </ a >
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222+ </ div >
223+ </ div >
224+ < div class ="row ">
225+ < div class ="col-sm-12 content-body ">
226+
227+ < 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 "> key_comp</ span > < span class ="cpp cpp23 " title ="C++23で追加 "> (C++23)</ span > </ h1 >
228+ < div itemprop ="articleBody "> < p > < div class ="codehilite "> < pre > < span > </ span > < code > < span class ="n "> key_compare</ span > < span class ="nf "> key_comp</ span > < span class ="p "> ()</ span > < span class ="k "> const</ span > < span class ="p "> ;</ span > < span class ="c1 "> // C++23</ span >
229+ </ code > </ pre > </ div >
230+ </ p >
231+ < h2 > 概要</ h2 >
232+ < p > コンテナに関連づけられたキー比較用の関数オブジェクトを返す。このオブジェクトはコンテナ内の二つの要素のキー値を比較するために利用できる。
233+ この比較オブジェクトはオブジェクトの構築時に与えられ、関数へのポインタでも関数オブジェクトでも良い。いずれの場合でも、これは同じ型の 2 つの引数をとり、< a href ="../../algorithm.html#strict-weak-ordering "> 狭義の弱順序</ a > に従って一つ目の引数が二つ目の引数より前のときに < code > true</ code > を返し、そうでないときに < code > false</ code > を返す。</ p >
234+ < 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 >
235+ < p > 比較オブジェクト。< code > key_compare</ code > はメンバ型であり、テンプレートパラメータ < code > Compare</ code > の別名として定義される。</ p >
236+ < 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 >
237+ < p > 定数時間。</ p >
238+ < h2 > 例</ h2 >
239+ < p > < div class ="yata " id ="e104560e572f39011d6590968dc6ab6953aa9321 "> < 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 >
240+ < span class ="cp "> #include</ span > < span class ="cpf "> < a href ="../../iostream.html "> <iostream></ a > </ span > < span class ="cp "> </ span >
241+
242+ < span class ="kt "> int</ span > < span class ="nf "> main</ span > < span class ="p "> ()</ span >
243+ < span class ="p "> {</ span >
244+ < 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 "> m</ span > < span class ="p "> ;</ span >
245+ < 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 "> key_compare</ span > < span class ="n "> comp</ span > < span class ="o "> =</ span > < span class ="n "> m</ span > < span class ="p "> .</ span > < span class ="n "> < span style ="color:#ff0000 "> key_comp()</ span > </ span > < span class ="p "> ;</ span >
246+
247+ < span class ="n "> < a href ="../../iostream/cout.html "> std::cout</ a > </ span > < span class ="o "> <<</ span > < span class ="n "> comp</ span > < span class ="p "> (</ span > < span class ="mi "> 1</ span > < span class ="p "> ,</ span > < span class ="mi "> 2</ span > < span class ="p "> )</ span > < span class ="o "> <<</ span > < span class ="n "> < a href ="../../ostream/endl.html "> std::endl</ a > </ span > < span class ="p "> ;</ span >
248+ < span class ="n "> < a href ="../../iostream/cout.html "> std::cout</ a > </ span > < span class ="o "> <<</ span > < span class ="n "> comp</ span > < span class ="p "> (</ span > < span class ="mi "> 3</ span > < span class ="p "> ,</ span > < span class ="mi "> 2</ span > < span class ="p "> )</ span > < span class ="o "> <<</ span > < span class ="n "> < a href ="../../ostream/endl.html "> std::endl</ a > </ span > < span class ="p "> ;</ span >
249+ < span class ="p "> }</ span >
250+ </ code > </ pre > </ div >
251+ </ div > </ p >
252+ < h3 > 出力</ h3 >
253+ < p > < pre > < code > 1
254+ 0
255+ </ code > </ pre > </ p >
256+ < h2 > バージョン</ h2 >
257+ < h3 > 言語</ h3 >
258+ < ul >
259+ < li > C++23</ li >
260+ </ ul >
261+ < h3 > 処理系</ h3 >
262+ < ul >
263+ < li > < a href ="../../../implementation.html#clang "> Clang</ a > : ??</ li >
264+ < li > < a href ="../../../implementation.html#gcc "> GCC</ a > : ??</ li >
265+ < li > < a href ="../../../implementation.html#icc "> ICC</ a > : ??</ li >
266+ < li > < a href ="../../../implementation.html#visual_cpp "> Visual C++</ a > : ??</ li >
267+ </ ul >
268+ < h2 > 関連項目</ h2 >
269+ < table border ="1 " bordercolor ="#888 " style ="border-collapse:collapse ">
270+ < thead >
271+ < tr >
272+ < th > 名前</ th >
273+ < th > 説明</ th >
274+ </ tr >
275+ </ thead >
276+ < tbody >
277+ < tr >
278+ < td > < code > < a href ="value_comp.html "> value_comp</ a > </ code > </ td >
279+ < td > 要素比較用の関数オブジェクトを返す</ td >
280+ </ tr >
281+ < tr >
282+ < td > < code > < a href ="value_compare.html "> value_compare</ a > </ code > </ td >
283+ < td > 要素値のキー部分で大小関係を判定する二項< a class ="cpprefjp-defined-word " data-desc ="boolを返す関数・関数オブジェクト。predicate "> 述語</ a > の型</ td >
284+ </ tr >
285+ </ tbody >
286+ </ table > </ div >
287+
288+ </ div >
289+ </ div >
290+ </ div >
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295+
296+
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