visualstudio 2010-关闭表单上的消息框回答问题

Question

我正试图使用此代码来关闭消息框特定答案的表单。我一直收到一个错误，说Yes和No都不属于DialogResult::。我基本上是直接从MS站点复制这个代码的，所以我不知道出了什么问题。帮助

private: System::Void Form1_FormClosing(System::Object^  sender, System::Windows::Forms::FormClosingEventArgs^  e) {
             if(!watchdog->Checked)
             {
                 if((MessageBox::Show("CAN Watchdog is currently OFF. If you exit with these settings, the SENSOWheel will still be engaged. To prevent this, please enable CAN Watchdog before closing. Would you still like to quit?", "Watchdog Warning", MessageBoxButtons::YesNo, MessageBoxIcon::Question) == DialogResult::No))
                 {
                     return;
                 }
                 else
                 {
                     close_Click(this, e);
                 }
             }
     }

Answer 1

if（（MessageBox:：Show（"…"，"看门狗警告"，MessageBoxButtons:：是否，MessageBoxIcon:：问题）==系统：：窗口：：窗体：：对话框结果：：否））{e->取消=true；//不要关闭}

Answer 2

DialogResult枚举和Form的DialogResult属性之间存在命名冲突。如果你想要前者，编译器会假设你指的是后者。

解决歧义的一种方法是完全限定您对枚举的引用：

if((MessageBox::Show("CAN Watchdog ... Would you still like to quit?", "Watchdog Warning", MessageBoxButtons::YesNo, MessageBoxIcon::Question) == System::Windows::Forms::DialogResult::No))

我在这个线程中找到了第二个方法；将using namespace System...语句移出namespace块，然后通过全局命名空间引用枚举。

if((MessageBox::Show("CAN Watchdog ... Would you still like to quit?", "Watchdog Warning", MessageBoxButtons::YesNo, MessageBoxIcon::Question) == ::DialogResult::No))

Answer 3

这是一个工作解决方案，它有一些额外的代码，这样您就可以看到全貌。在这个例子中，有一些正在工作的BackgroundWorker必须在应用程序关闭之前停止。

#pragma region Start/Stop/Exit
    private: System::Void backgroundWorker1_RunWorkerCompleted(System::Object^  sender, System::ComponentModel::RunWorkerCompletedEventArgs^  e) {
                 if(e->Cancelled)     
                 {
                     rtbLog->Text = rtbLog->Text  +  ">>> Application stopped n";  
                 }
                 else   
                 {
                     rtbLog->Text = rtbLog->Text  +  ">>> Application completed n";  
                 }
             }
    private: System::Void startToolStripMenuItemStart_Click(System::Object^  sender, System::EventArgs^  e) 
             {
                 if (backgroundWorker1->IsBusy == false) 
                 { 
                     backgroundWorker1->RunWorkerAsync(1);  //starting background worker
                 }
             }
    private: System::Void stopToolStripMenuItemStop_Click(System::Object^  sender, System::EventArgs^  e) 
             {
                 if (backgroundWorker1->IsBusy == true && backgroundWorker1->WorkerSupportsCancellation == true) 
                 {     
                     backgroundWorker1->CancelAsync(); 
                 } 
             }    
    private: System::Void Form1_FormClosing(System::Object^  sender, System::Windows::Forms::FormClosingEventArgs^  e) {
                 if((MessageBox::Show("Would you still like to quit?", "Warning", MessageBoxButtons::YesNo, MessageBoxIcon::Question) == 
                     System::Windows::Forms::DialogResult::No))                  
                 {
                     e->Cancel = true;    // Don't close and BackgroundWoker is executing.             
                 }  
                 else
                 {
                     if (backgroundWorker1->IsBusy == true && backgroundWorker1->WorkerSupportsCancellation == true) 
                     {     
                         backgroundWorker1->CancelAsync(); 
                     } 
                 } 
             }
    private: System::Void exitToolStripMenuItemExit_Click(System::Object^  sender, System::EventArgs^  e) {
                 Application::Exit(); // The user wants to exit the application. Close everything down.
             }
#pragma endregion