Showing a list of errors in MessageBox show method

I'm trying to figure out a way to show a listing of validation errors in my app using MessageBox.Show. So fa开发者_JS百科r I have this:

    private bool FormIsValid()
    {
        bool isValid = true;
        List<string> strErrors = new List<string>();

        if (!(txtFirstName.Text.Length > 1) || !(txtLastName.Text.Length > 1))
        {
            strErrors.Add("You must enter a first and last name.");
            isValid = false;
        }
        if (!txtEmail.Text.Contains("@") || !txtEmail.Text.Contains(".") || !(txtEmail.Text.Length > 5))
        {
            strErrors.Add("You must enter a valid email address.");
            isValid = false;
        }
        if (!(txtUsername.Text.Length > 7) || !(pbPassword.Password.Length > 7) || !ContainsNumberAndLetter(txtUsername.Text) || !ContainsNumberAndLetter(pbPassword.Password))
        {
            strErrors.Add("Your username and password most both contain at least 8 characters and contain at least 1 letter and 1 number.");
            isValid = false;
        }

        if (isValid == false)
        {
            MessageBox.Show(strErrors);
        }

        return isValid;
    }

But alas, you cannot use a List of type String inside the Show method. Any ideas?

You could use the following:

        List<string> errors = new List<string>();
        errors.Add("Error 1");
        errors.Add("Error 2");
        errors.Add("Error 3");

        string errorMessage = string.Join("\n", errors.ToArray());
        MessageBox.Show(errorMessage);

Why not use a string?

private bool FormIsValid()
{
    bool isValid = true;
    string strErrors = string.Empty;

    if (!(txtFirstName.Text.Length > 1) || !(txtLastName.Text.Length > 1))
    {
        strErrors = "You must enter a first and last name.";
        isValid = false;
    }
    if (!txtEmail.Text.Contains("@") || !txtEmail.Text.Contains(".") || !(txtEmail.Text.Length > 5))
    {
        strErrors += "\nYou must enter a valid email address.";
        isValid = false;
    }
    if (!(txtUsername.Text.Length > 7) || !(pbPassword.Password.Length > 7) || !ContainsNumberAndLetter(txtUsername.Text) || !ContainsNumberAndLetter(pbPassword.Password))
    {
        strErrors += "\nYour username and password most both contain at least 8 characters and contain at least 1 letter and 1 number.";
        isValid = false;
    }

    if (isValid == false)
    {
        MessageBox.Show(strErrors);
    }

    return isValid;
}