strange string error
<p><strong>program:</strong></p>

<pre><code> CCompussGradientOperator dlg;
  string p = "preqitt";
  string k = "Kirnch";
  string r3 = "Robison";
  f(dlg.DoModal() == IDOK)
      {
    CDib dib = m_Dib;
    BOOL ret = FALSE;

    if(dlg.m_Combo_Operators == p )
    {
       switch(dlg.m_nFunction)
       {
       case 0: ret ;
       }
    }

}
</code></pre>

<p><strong>error</strong>:</p>

<p>Error   18  error C2065: 'string' : undeclared identifier   d:\2nd\imagetool\imagetooldoc.cpp   870 1   ImageTool</p>

<p>string is a data type then why it does make me error.. its strange for me...
any one can help me ..thanks </p>
