cannot convert from 'string' to 'System.Windows.Forms.MessageBoxIcon

Question

I'm working on a piece of software that lets you generate your own customized Messagebox. My code has no errors until I try and put in the MessageBoxButtons and MessageBoxIcon. Then, I get Error

2 Argument 3: cannot convert from 'string' to 'System.Windows.Forms.MessageBoxButtons' and Error 3 Argument 4: cannot convert from 'string' to 'System.Windows.Forms.MessageBoxIcon'. What is the issue here?

if (textBoxX1.Text == String.Empty)
    MessageBox.Show("You must enter a title.");
else if (richTextBoxEx1.Text == String.Empty)
    MessageBox.Show("You must enter a body.");
else
{
    string previewtype = string.Empty;
    string previewbutton = string.Empty;
    if (radioButton1.Checked == true)
        previewtype = "MessageBoxIcon.Error";
    else if (radioButton2.Checked == true)
        previewtype = "MessageBoxIcon.Information";
    else if (radioButton3.Checked == true)
        previewtype = "MessageBoxIcon.Exclamation";
    else if (radioButton4.Checked == true)
        previewtype = "MessageBoxIcon.Question";
    if (radioButton8.Checked == true)
        previewbutton = "MessageBoxButtons.AbortRetryIgnore";
    else if (radioButton7.Checked == true)
        previewbutton = "MessageBoxButtons.OK";
    else if (radioButton6.Checked == true)
        previewbutton = "MessageBoxButtons.OKCancel";
    else if (radioButton5.Checked == true)
        previewbutton = "MessageBoxButtons.RetryCancel";
    else if (radioButton9.Checked == true)
        previewbutton = "MessageBoxButtons.YesNo";
    else if (radioButton10.Checked == true)
        previewbutton = "MessageBoxButtons.YesNoCancel";
    MessageBox.Show(textBoxX1.Text, richTextBoxEx1.Text, previewbutton, previewtype);
}

Answer 1

The error is because you're passing strings to MessageBox.Show(), where you should be passing MessageBoxButtons and MessageBoxIcon. In other words, you cannot do this:

MessageBox.Show("Some text", "a caption", "MessageBoxButtons.AbortRetryIgnore", "MessageBoxIcon.Error");

But you can do this:

MessageBox.Show("Some text", "a caption", MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Error);

Your previewtype and previewbutton variables should be defined as the actual types, not as strings:

MessageBoxIcon previewtype;
MessageBoxButtons previewbutton;

If we update your sample to use the correct data types, it looks like this:

if (textBoxX1.Text == String.Empty)
    MessageBox.Show("You must enter a title.");
else if (richTextBoxEx1.Text == String.Empty)
    MessageBox.Show("You must enter a body.");
else
{
    MessageBoxIcon previewtype;
    MessageBoxButtons previewbutton;
    if (radioButton1.Checked == true)
        previewtype = MessageBoxIcon.Error;
    else if (radioButton2.Checked == true)
        previewtype = MessageBoxIcon.Information;
    else if (radioButton3.Checked == true)
        previewtype = MessageBoxIcon.Exclamation;
    else if (radioButton4.Checked == true)
        previewtype = MessageBoxIcon.Question;
    if (radioButton8.Checked == true)
        previewbutton = MessageBoxButtons.AbortRetryIgnore;
    else if (radioButton7.Checked == true)
        previewbutton = MessageBoxButtons.OK;
    else if (radioButton6.Checked == true)
        previewbutton = MessageBoxButtons.OKCancel;
    else if (radioButton5.Checked == true)
        previewbutton = MessageBoxButtons.RetryCancel;
    else if (radioButton9.Checked == true)
        previewbutton = MessageBoxButtons.YesNo;
    else if (radioButton10.Checked == true)
        previewbutton = MessageBoxButtons.YesNoCancel;
    MessageBox.Show(textBoxX1.Text, richTextBoxEx1.Text, previewbutton, previewtype);