WPF应用

   private void button1_Click(object sender, RoutedEventArgs e)
        {
            calculate sa = new calculate(int.Parse(textBox1.Text),int.Parse(textBox3.Text),textBox2.Text);
            if (sa.answer == int.Parse(textBox4.Text))
            {
                MessageBox.Show("回答正确");
            }
            else
            {
                MessageBox.Show("回答错误");
            
            }

 interface chapter
    {
        int answer { get; }
    }
    class calculate:chapter
    {
           private int x1;
        private int x2;
        private string Operator;
        public int result;
        public calculate(int x1, int x2, string Operator)
        {
            this.x1 = x1;
            this.x2 = x2;
            this.Operator = Operator;
       

        }
        public int answer
        {
            get {

                if (Operator == "+")
                {
                    result = x1 + x2;

                }
                if (Operator == "-")
                {

                    result = x1 - x2;

                }
                if (Operator == "*")
                {

                    result = x1 * x2;

                }
                 if (Operator == "/")
                {

                    result = x1 / x2;

                }
                return result;
            }
        }

    }
}