关闭消息框上的表单回答问题

Question

我正在尝试使用此代码来关闭消息框的特定答案上的表单。我不断收到一条错误消息，指出 Yes 和 No 都不属于 DialogResult::。我基本上直接从 MS 网站复制了这段代码，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("...", "Watchdog Warning", MessageBoxButtons::YesNo, MessageBoxIcon::Question) == 
    System::Windows::Forms::DialogResult::No))                  
{
   e->Cancel = true;    // don't close              
}                  

Answer 2

DialogResult 枚举与 Form 的 DialogResult 属性之间存在命名冲突。您想要前者，编译器假设您指的是后者。

解决歧义的一种方法是完全限定对枚举的引用：

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

我在此找到了第二种方法 线程;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

这是工作解决方案，其中有一些额外的代码，以便您可以看到整个图片。在此示例中，有一些正在运行的 BackgroundWorker 在应用程序关闭之前必须停止。

#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