在C#中，我经常喜欢创建一个名为“IntTextBox”的自定义类，它只允许有效整数存在于“Text”属性中。

public class IntTextBox : TextBox
{
    string origin = "0";
    //A string to return to if the user-inputted text is not an integer.
    public IntTextBox()
    {
        Text = "0";
        TextChanged += new EventHandler(IntTextBox_TextChanged);
    }
    private void IntTextBox_TextChanged(object sender, EventArgs e)
    {
        int temp;
        if(int.TryParse(Text,out temp))
        //If the value of "Text" can be converted into an integer.
        {
            origin = Text;
            //"Save" the changes to the "origin" variable.
        }
        else
        {
            Text = origin;
            //Return to the previous text value to remove invalidity.
        }
    }
}

我试图在C++中模仿这一点，没有明显的错误，但是当我试图将其添加到我的表单中时，Visual Studio说“未能加载项目'IntTextBox'。它将从工具箱中删除。这是我迄今为止尝试过的代码。

public ref class IntTextBox : public System::Windows::Forms::TextBox
{
    public:
        IntTextBox()
        {
            Text = "0";
            TextChanged += gcnew System::EventHandler(this, &AIMLProjectCreator::IntTextBox::IntTextBox_TextChanged);
        }
    private:
        String^ origin = "0";
        System::Void IntTextBox_TextChanged(System::Object^ sender, System::EventArgs^ e)
        {
            int temp;
            if (int::TryParse(Text, temp))
            {
                origin = Text;
            }
            else
            {
                Text = origin;
            }
        }
};