title: Is it good practice to use multiple namespace in same C++ source file?
body: <p>I want to include more than one namespace in the same .cpp file.</p>
  
  <p>While <code>std</code> is widely used, the namespace <code>z3</code> will be used in about 10% of a 25 KLOC file.</p>
  
  <p>Will it be a good practice to use both as </p>
  
  <pre><code>    using namespace std;
      using namespace z3;
  </code></pre>
  
  <p>I am thinking of using only <code>std</code> and then use the <code>Z3</code> methods by mentioning the namespase whenever required. Like,</p>
  
  <pre><code>    using namespace std;
  
      z3::context c;
      z3::solver s;
  </code></pre>
  
  <p>Which of these is better practice?</p>
  
  <p>I do not want to rename them into one namespace.</p>
  
  <p>Thanks and regards,
  Sukanya</p>