title: Error checking so that I don't divide by 10 everytime
body: <p>How can I check to see if the textbox is empty and then only divide by that number of <code>int</code>. As you can see now I will divide by 10 everytime so now I need help with error checking.</p>
  
  <pre><code>namespace Assignment1_White
  {
      public partial class Form1 : Form
      {
          public Form1()
          {
              InitializeComponent();
          }
  
          private void button1_Click(object sender, EventArgs e)
          {
              int num1;
              int num2;
              int num3;
              int num4;
              int num5;
              int num6;
              int num7;
              int num8;
              int num9;
              int num10;
              int answer;
  
              num1 = int.Parse(num100.Text);
              num2 = int.Parse(num200.Text);
              num3 = int.Parse(num300.Text);
              num4 = int.Parse(num400.Text);
              num5 = int.Parse(num500.Text);
              num6 = int.Parse(num600.Text);
              num7 = int.Parse(num700.Text);
              num8 = int.Parse(num800.Text);
              num9 = int.Parse(num900.Text);
              num10 = int.Parse(num1000.Text);
  
  
  
              answer = (num1 + num2 + num3 + num4 + num5 + num6 + num7 + num8 + num9 +num10)/10;
              MessageBox.Show(answer.ToString());
  </code></pre>