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[英]Do I need to free wchar memory allocated when using 'new' or does delete[] also free it?
[英]Do I need to free the memory in this case somehow?
我有一個指針State *state;
這是其他狀態繼承的類。 我做state = new GameState;
如果我將對象狀態從 GameState 指向的內容更改為其他內容,我是否需要以某種方式釋放內存?
如果您的意思是State* state
不擁有該對象,您將需要執行以下操作:
// create states
State* game_state = new GameState();
State* menu_state = new MenuState();
// set current state
State* state = game_state;
// ... do somethings ...
// delete states
delete game_state;
game_state = nullptr;
delete menu_state;
menu_state = nullptr;
state = nullptr;
如果您想編寫現代代碼,請使用:
// create states
auto game_state = make_unique<GameState>();
auto menu_state = make_unique<MenuState>();
// set current state
State* state = game_state.get();
// ... do somethings ...
// no need to delete states
state = nullptr;
您還可以使用 shared_ptr 和 weak_ptr 的組合。
如果不使用智能指針,則需要對擁有該對象的任何對象調用delete
。
如果State* state
確實擁有該對象,則您需要執行以下操作:
// create current state
State* state = new GameState();
// ... do somethings ...
// switch state
delete state;
state = new MenuState();
// ... do somethings ...
// delete state
delete state;
state = nullptr;
並使用智能指針:
// create current state
unique_ptr<State> state = make_unique<GameState>();
// ... do somethings ...
// switch state (old state automatically deleted)
state = make_unique<MenuState>();
// ... do somethings ...
// delete state
state = nullptr;
這是一個簡單的規則:如果您編寫new
,請為其編寫一個delete
。 如果在堆上分配內存,則必須釋放它,否則會發生內存泄漏,這就是沒有內置垃圾收集功能的語言的本質。 所以如果你寫:
State *state;
state = new GameState;
您還必須執行以下操作:
delete state;
此外,請考慮使用智能指針,它們更安全,如果您想編寫現代C++,您應該真正研究它們。
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