如何從矢量中刪除元素？

Question

我正在開發一個簡單的基於控制檯的電子郵件應用程序。

在我的應用程序中，郵件存儲在std::vector中，我想添加刪除郵件的可能性。

如何從矢量中刪除元素？

這裏是我的代碼：

//MAIN MENU OPTION 1 SELECTED: 
// print list of all messages to the console 
void viewInbox() { 
    vector<Message> inbox{ 
     Message("jayleno@hotmail.com", "Knife you tonight", "Hey Sam, what kind of suit do you wanna be buried in?!"), 
     Message("paypalservices@hotmail.com", "Urgent from paypal.com", "Dear paypal user, someone has hacked your account. Give us your password now so we change it!"), 
    }; 

    cout << "You have " << inbox.size() << " new messages.\n"; 
    cout << "Index  Subject" << '\n'; 

    for (int i = 0; i < inbox.size(); ++i) 
     std::cout << "Message " << i << ": " << inbox[i].getSubject() << '\n'; 

    cout << "Please enter number of message you would like to view\n"; 
    int read; 
    cin >> read; 
    cout << "From: " << inbox[read].getAddress() << '\n'; 
    cout << "Subject: " << inbox[read].getSubject() << '\n'; 
    cout << inbox[read].getMessageText() << '\n'; 

    cout << "To erase this message press 1\n"; 
    //Code here for deleting a message... 
}//end of viewInbox() 

Answer 1

若要擦除從矢量使用vector::erase這需要一個迭代的消息。

獲取迭代器到特定消息的最簡單方法是使用inbox.begin() + message_number。

我已經重構你的代碼轉換成更小的功能，使代碼更易於與工作：

void viewMessage(vector<Message>& messages, size_t message_number) { 
    vector<Message>::iterator message = messages.begin() + message_number; 
    cout << "From: " << message->getAddress() << endl; 
    cout << "Subject: " << message->getSubject() << endl; 
    cout << message->getMessageText() << endl; 

    cout << "To erase this message press 1\n"; 
    int erase; 
    cin >> erase; 
    // Maybe do some error checking on cin... 
    if (erase == 1) { 
     messages.erase(message); 
    } 
    } 

    void viewMessages(vector<Message>& messages){ 
    auto inbox_size = messages.size(); 
    cout << "You have " << inbox_size << " new messages.\n"; 
    cout << "Index  Subject" << '\n'; 

    for (size_t i = 0u; i != inbox_size; ++i) { 
     std::cout << "Message " << i << ": " << messages[i].getSubject() << '\n'; 
    } 

    cout << "Please enter number of message you would like to view\n"; 
    size_t message_number; 
    cin >> message_number; 
    // Maybe do some error checking on cin... 
    // And some bounds checking of message_number... 
    viewMessage(messages, message_number); 
    } 

void viewInbox() { 
    vector<Message> inbox{ 
    Message{ "jayleno@hotmail.com", "Knife you tonight", "Hey Sam, what kind of suit do you wanna be buried in?!" }, 
    Message{"paypalservices@hotmail.com", "Urgent from paypal.com", "Dear paypal user, someone has hacked your account. Give us your password now so we change it!"}, 
    }; 
    viewMessages(inbox); 
    // Maybe call viewMessages again to see results of erase... 
} 

正如我曾評論，注意你的輸入錯誤檢查。