title: String operation to copy number of character to a new string location for example S[0]
body: <p>Suppose I have </p>
  
  <pre><code>string s1="100000111010"
  string s2;
  </code></pre>
  
  <p>what is the best way to have</p>
  
  <pre><code>s2[0]="1000"
  s2[1]="0011"
  s2[2]="1010";
  </code></pre>