title: c++ class declaration error?
body: <p>guys i am new to c++ 
  i am trying to create an class these are my files</p>
  
  <pre><code>//main.cpp
  #include &lt;iostream&gt;
  #include "testing/test.h"
  #include &lt;string&gt;
  using namespace std;
  
  
  int main(void)
  {
  
   test c;
   c.set_url("e");
  
  }
  </code></pre>
  
  <p>test.h</p>
  
  <pre><code>#ifndef TEST_H_
  #define TEST_H_
  #include&lt;string&gt;
  class test {
  
    public:
  
      void testing(string url);
  
  
  };
  
  #endif /* TEST_H_ */
  
  
  
       //test.cpp
  
  #include &lt;iostream&gt;
  #include&lt;string&gt;
  using namespace std;
  
  
  
  void crawl::testing (string url) {
   cout&lt;&lt; "i am from test class";
  }
  </code></pre>
  
  <p>i am getting error: ‘string’ has not been declared error</p>