Can anyone help me understand this error? "definition of implicitly-declared ‘classA::classA()’"
<p>Heres the code:</p>

<pre><code>#include &lt;cstdlib&gt;
#include &lt;iostream&gt;
using namespace std;

class classA
{                   
      protected:
                void setX(int a);

      private:
              int p;
};

classA:: classA()
{                      //error here.
 p = 0;
}

void classA:: setX(int a)
{
 p = a;    
}

int main()
{   
    system("PAUSE");
    return EXIT_SUCCESS;
}
</code></pre>
