title: how to increase the value of an integer in a string
body: <p>Ok I currently have this code</p>
  
  <pre><code>        public int i = 0; //this is outside of the private void button1_click
          string str = txtEmail.Text;
          int pos = str.LastIndexOf("@");
          string str2 = str.Substring(pos);
          string str3 = str.Substring(0, str.LastIndexOf("@"));
          txtEmail.Text = str3 + i++ + str2;
  </code></pre>
  
  <p>it splits the email into 2 string then combines them with an integer between them, But I want it to change the integer. But that code just makes it lets saying the text becomes awesome1@email.com when i press the button to increase the 1 to a 2 it just does this instead. awesome12@email.com and so on. how do i get it to just add 1 to the 1 and not put a 2 next to the 1?</p>