C++ Undeclared Identifier program
<p>I'm getting an undeclared problem but i don't seem to see the error my self .. I'm trying to display the instructors name by change in it when i debug and displaying the changed name .if you could please help it would be appreciate it.</p>

<p>GradeBook.cpp</p>

<pre><code>// Fig. 3.12: GradeBook.cpp

// GradeBook member-function definitions. This file contains
// implementations of the member functions prototyped in GradeBook.h.
#include &lt;iostream&gt;
#include "GradeBook.h" // include definition of class GradeBook
using namespace std;

// constructor initializes courseName with string supplied as argument
GradeBook::GradeBook( string name )
{
   setCourseName( name );// call set function to initialize courseName
   setInstructorName( name );
} // end GradeBook constructor

// function to set the course name
void GradeBook::setCourseName( string name )
{
   courseName = name; // store the course name in the object
} // end function setCourseName

// function to get the course name
string GradeBook::getCourseName()
{
   return courseName; // return object's courseName
} // end function getCourseName

// FUNCTION TO SET THE COURSE INSTRUCTOR NAME
void GradeBook::setInstructorName( string name )
{
   InstructorName = name; // store the course name in the object
} // end function setCourseName

// FUNCTION TO GET THE COURSE INSTRUCTOR NAME
string GradeBook::getInstructorName()
{
   return InstructorName; // return object's InstructorName
} // end function getCourseName




// display a welcome message to the GradeBook user
void GradeBook::displayMessage()
{
   // call getInstructorName to get the InstructorName
   cout &lt;&lt; "This course is presented by \n" &lt;&lt; getInstructorName() 
      &lt;&lt; "!" &lt;&lt; endl;
} // end function displayMessage
</code></pre>

<p>Here is my header GradeBokk.h</p>

<pre><code>// Fig. 3.11: GradeBook.h



// GradeBook class definition. This file presents GradeBook's public 
// interface without revealing the implementations of GradeBook's member
// functions, which are defined in GradeBook.cpp.
#include &lt;string&gt; // class GradeBook uses C++ standard string class
using namespace std;

// GradeBook class definition
class GradeBook
{
public:
   GradeBook( string ); // constructor that initializes courseName
   void setCourseName( string ); // function that sets the course name
   string getCourseName(); // function that gets the course name
   void setInstructorName( string ); //FUNCTION THAT SETS THE COURSE INSTRUCTOR NAME
   string getInstructorName(); // FUNCTION THAT GETS THE COURSE INSTRUCTOR NAME
   void displayMessage(); // function that displays a welcome message
private:
   string courseName; // course name for this GradeBook
}; // end class GradeBook  
</code></pre>
