C で値渡し参照と右辺値参照渡しをいつ使用するか?

値渡しと右辺値渡しの複雑さの参照

はじめに:

C では、パスの選択値による参照または右辺値参照による渡しは、関数のセマンティクスと効率に大きな影響を与える可能性があります。これら 2 つのパラメーター受け渡しメカニズムの違いを理解することは、効果的でパフォーマンスの高いコードを作成するために重要です。

値による受け渡しと右側の値による受け渡しのリファレンス

パラメーター宣言:

値渡し:

<code class="cpp">void foo(Widget w);
````

**Pass by Rvalue Reference:**</code>

void foo(Widget&& w);

#### Ownership Semantics:

* **Pass by Value:** Caller's object is copied into the function, and the copy is destroyed when the function exits. Ownership is transferred to the function.
* **Pass by Rvalue Reference:** Caller's object is moved into the function, and the caller relinquishes ownership. The moved object's resources are directly accessed within the function.

#### Implications for Interface:

* Pass by value implies that the caller expects the object to remain unchanged.
* Pass by rvalue reference suggests that the function may modify or destroy the object.

**Efficiency:**

* Pass by rvalue reference is potentially more efficient because it eliminates the need for an additional copy.
* Pass by value may result in a single move or copy constructor call, depending on the compiler's optimization level.

**Explicitness:**

* Pass by rvalue reference forces the caller to explicitly move the argument into the function, making the transfer of ownership clear.
* Pass by value implicitly copies the argument, which can lead to unexpected behavior if the intention is to move ownership.

### Conclusion:

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