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# size | ||
* ranges[meta header] | ||
* std::ranges[meta namespace] | ||
* as_const_view[meta class] | ||
* function[meta id-type] | ||
* cpp23[meta cpp] | ||
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```cpp | ||
constexpr auto size() requires sized_range<V>; // (1) | ||
constexpr auto size() const requires sized_range<const V>; // (2) | ||
``` | ||
* sized_range[link /reference/ranges/sized_range.md] | ||
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## 概要 | ||
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`view`の要素数を取得する。 | ||
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この関数で得られる`as_const_view`の要素数は、元のRange(`V`)の要素数と一致する。 | ||
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## 戻り値 | ||
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入力`view`(`V`)のオブジェクトを`base_`というメンバに保持するとして | ||
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- (1) : `return ranges::size(base_);` | ||
- (2) : `return ranges::size(base_);` | ||
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## 例 | ||
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```cpp example | ||
#include <ranges> | ||
#include <vector> | ||
#include <iostream> | ||
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int main() { | ||
std::vector<int> vec = {1, 2, 3, 4, 5}; | ||
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std::ranges::as_const_view acv{vec}; | ||
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std::cout << acv.size() << '\n'; | ||
std::cout << vec.size() << '\n'; | ||
} | ||
``` | ||
* size[color ff0000] | ||
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### 出力 | ||
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``` | ||
5 | ||
5 | ||
``` | ||
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## バージョン | ||
### 言語 | ||
- C++23 | ||
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### 処理系 | ||
- [Clang](/implementation.md#clang): ?? | ||
- [GCC](/implementation.md#gcc): 13.1 | ||
- [Visual C++](/implementation.md#visual_cpp): 2022 Update 6 | ||
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## 参照 | ||
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- [P2278R4 `cbegin` should always return a constant iterator](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2278r4.html) |