在对话框关闭或执行下一个操作之前，我必须单击多次……我该如何解决这个问题？

Question

Here is my C# code:

private void StudentReg_FormClosing(object sender, FormClosingEventArgs e)
{
    DialogResult dialog = MessageBox.Show("Do you really want to close this window?", "Exit", MessageBoxButtons.YesNo);

    if (dialog == DialogResult.Yes) 
    {
        Application.Exit();
    }
    else if (dialog == DialogResult.No)
    {
        e.Cancel = true;
    }
}

Answer 1

I doubt if you really want Application.Exit(); : you prompt (bold is mine)

Do you really want to close this window

It is the window ( Form ), not the entire Aplication you want to close. If it's your case, you can just do nothing and let the form (window) close itself:

private void StudentReg_FormClosing(object sender, FormClosingEventArgs e)
{
    // Cancel closing (i.e. do NOT close the form) if and only if user's chosen "No".
    // Do nothing (i.e. do not cancel) in other cases (let the form be closed)
    // So we assign true (cancel) if "No" has been pressed, false otherwise 
    e.Cancel = MessageBox.Show(
      "Do you really want to close this window?", 
      "Exit", 
       MessageBoxButtons.YesNo) == DialogResult.No; 
}

Answer 2

Depending on how you setup your application like if this is your main form or you have multiple you may need to just remove the event to avoid duplicate calls to it.

Remove the event handler before calling application.exit and I think your issue will be solved.

This is psuedo-code.

private void StudentReg_FormClosing(object sender, FormClosingEventArgs e)
        {
            DialogResult dialog = MessageBox.Show("Do you really want to close this window?", "Exit", MessageBoxButtons.YesNo);
            if(dialog == DialogResult.Yes) 
            {
                StudentReg.FormClosing -= StudentReg_FormClosing; 
                Application.Exit();
           
            }
            else if(dialog == DialogResult.No)
            {
                e.Cancel = true;

                }
        }