title: Why header string is required for cout?
body: <p>Why in the below code without  including "string"  header I can declare string variable.
  But compiler complains  only for cout, when I try to print the string.</p>
  
  <p>What information "string" header consists of ?</p>
  
  <pre><code>  #include &lt;iostream&gt;
  //#include "string"
  
  int main () 
  {
      std::string str="SomeWorld";
  
      std::cout&lt;&lt;str&lt;&lt;std::endl;
  
    return 0;
  }
  </code></pre>