C++: call class method from a non-class function
<p>I want to write a help function which calls a class method:</p>

<p>foo.h</p>

<pre><code>class cls{
  public:
  void fun();
  void fun1();
};
</code></pre>

<p>foo.cpp</p>

<pre><code>void cls::fun(){
  helperFun();
}

void helperFun(){
  fun1();//how to call fun1() here?
}
</code></pre>

<p>How should I do it, or what's the best way of doing it?</p>
