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std::map::find

提供: cppreference.com
< cpp‎ | container‎ | map

 
 
 
std::map
メンバ関数
Original:
Member functions
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map::map
map::~map
map::operator=
map::get_allocator
要素アクセスの循環参照を解除するために使用されている
Original:
Element access
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map::at
map::operator[]
イテレータ
Original:
Iterators
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map::begin
map::cbegin

(C++11)
map::end
map::cend

(C++11)
map::rbegin
map::crbegin

(C++11)
map::rend
map::crend

(C++11)
容量
Original:
Capacity
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map::empty
map::size
map::max_size
修飾子
Original:
Modifiers
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map::clear
map::insert
map::emplace(C++11)
map::emplace_hint(C++11)
map::erase
map::swap
ルック
Original:
Lookup
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map::count
map::find
map::equal_range
map::lower_bound
map::upper_bound
オブザーバー
Original:
Observers
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map::key_comp
map::value_comp
 
iterator find( const Key& key );
const_iterator find( const Key& key ) const;
キーkeyを持つ要素を検索します。
Original:
Finds an element with key key.
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目次

[編集] パラメータ

key -
検索する要素のキー値
Original:
key value of the element to search for
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[編集] 値を返します

キーkey持つ要素を指すイテレータ。このような要素が見つからない場合は、過去ツーエンド(end()を参照)イテレータが返されます.
Original:
Iterator to an element with key key. If no such element is found, past-the-end (see end()) iterator is returned.
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[編集] 複雑

Logarithmic in the size of the container.

[編集] も参照してください

特定のキーと一致する要素の数を返します
Original:
returns the number of elements matching specific key
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(パブリックメンバ関数) [edit]
特定のキーと一致する要素の範囲を返します
Original:
returns range of elements matching a specific key
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(パブリックメンバ関数) [edit]


[編集]

Demonstrates the risk of accessing non-existing elements via operator [].

#include <string>
#include <iostream>
#include <map>
 
int main()
{
    typedef std::map<std::string,int>  mapT;
 
    mapT my_map;
    my_map["first"]=  11;
    my_map["second"]= 23;
 
    mapT::iterator  it= my_map.find("first");
    if( it != my_map.end() ) std::cout << "A: " << it->second << "\n";
 
    it= my_map.find("third");
    if( it != my_map.end() ) std::cout << "B: " << it->second << "\n";
 
    // Accessing a non-existing element creates it
    if( my_map["third"] == 42 ) std::cout << "Oha!\n";
 
    it= my_map.find("third");
    if( it != my_map.end() ) std::cout << "C: " << it->second << "\n";
 
    return 0;
}

Output:

A: 11
C: 0