title: Use of colon in C# constructor header
body: <p>Below is the constructor of a <code>struct</code> named Complex with two member variables, Real and Imaginary:</p>
  
  <pre><code>public Complex(double real, double imaginary) : this()
  {
   Real = real;
   Imaginary = imaginary;
  }
  </code></pre>
  
  <p>What is the use of the part after the colon in the function header? </p>