Is it good practice to use multiple namespace in same C++ source file? : <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>
