c++ class declaration error?
<p>hello 
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>
