std::future_error

 

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std::future_error

成員函式

future_error::future_error

future_error::operator=

future_error::code

future_error::what

 

在標頭檔案 <future> 中定義
class future_error;		(C++11 起)

類 std::future_error 定義了一個異常物件，當執行緒庫中處理非同步執行和共享狀態（std::future, std::promise 等）的函式失敗時丟擲。與 std::system_error 類似，此異常攜帶一個與 std::error_code 相容的錯誤碼。

繼承圖

成員函式

(建構函式)	建立 std::future_error 物件 (公有成員函式)
operator=	替換 std::future_error 物件 (公有成員函式)
code	返回錯誤碼 (公有成員函式)
what	返回特定於錯誤碼的解釋性字串 (公有成員函式)

繼承自 std::logic_error

繼承自 std::exception

成員函式

(解構函式) [虛擬函式]	銷燬異常物件 (std::exception 的虛公有成員函式)
what [虛擬函式]	返回解釋字串 (std::exception 的虛公有成員函式)

示例

執行此程式碼

#include <future>
#include <iostream>
 
int main()
{
    std::future<int> empty;
    try
    {
        int n = empty.get(); // The behavior is undefined, but
                             // some implementations throw std::future_error
    }
    catch (const std::future_error& e)
    {
        std::cout << "Caught a future_error with code \"" << e.code()
                  << "\"\nMessage: \"" << e.what() << "\"\n";
    }
}

可能的輸出

Caught a future_error with code "future:3"
Message: "No associated state"

參閱

future_errc (C++11)

標識 future 錯誤程式碼 (列舉)