Undefined reference to ...

Question

I think I declared and implemented the class 'GradeBook' in 'GradeBook.h' and 'GradeBook.cpp' files respectively. I also put the files in the same folder with the main.cpp file. However, I get the the errors

1) 'undefined reference to 'GradeBook::GradeBook(std::string)'.
2)'undefined reference to 'GradeBook::displayMessage()' where displayMessage is a public member function.

My Header and Source Files of the class are as follows

Header File:

#include <iostream>
#include <string>
using namespace std;

class GradeBook
{
public:
GradeBook(string name);
void setCourseName(string name);
string getCourseName();
void displayMessage();

private:
string courseName;
};

Source Code:

#include <iostream>
#include <string>
#include "GradeBook.h"
using namespace std;

GradeBook::GradeBook(string name)
{
courseName = name;
}

GradeBook::setCourseName(string name)
{
if (name.length() <= 25)
courseName = name;
if (name.length() > 25)
{
courseName = name.substr(0,25);

cout << "Name" << name << "exceeds 25 character.\n"
<< "Limiting course name to first 25 characters.\n"
}
}

GradeBook::getCourseName()
{
return courseName;
}

GradeBook::displayMessage()
{
cout << "Welcome to grade book for\n" << getCourseName() << endl;
}

Test Code:

#include <iostream>
#include <string>
#include "GradeBook.h"
using namespace std;

int main()
{
string name = "Default Name";
GradeBook gradeBook1(name);

gradeBook1.displayMessage();
}

I use CodeBlocks IDE to compile the code.
Is there anyone who knows what is my mistake.!

Answer 1

I was referring to your class method definition outside the class, not the method declaration. You missed out the return types.

Answer 2

Function return type not defined during class method definition.

Answer 3

It is constructor, not function

Answer 4

Thanks, I corrected it but the error is still there