class templates -linker errors

[tones1986]

Hey folks,

I am working on a project (its a continuation of my previous project)... but with a few additions. First off, i have to use class templates... I have used them before, but not when working with multiple class definitions and multiple files.

Below i will post sections of my Person.h, and Person.cpp files. I am getting linker errors with all of my functions when trying to edit them to work with templates. I am sure i am missing something rather obvious...

Person.h

#define PERSON_H

#include "340.h"

template <class T>
class Person;

template <class T>
class Person {
	public:
      Person();
      virtual ~Person();
      void setFirstName(T &x);
      T getFirstName() const;
      void setLastName(T &x);
      T getLastName() const;
      void setSSN(T &x);
      T getSSN() const;
      void setDOB(T &x);
      T getDOB() const;
      void setGender(T &x);
      T getGender() const;
      
    private:
      string firstName;
      string lastName;
      string SSN;
      string DOB;
      string gender;
};

#endif //PERSON_H

Person.cpp

#include "Person.h"

/****************************************************************
   FUNCTION:   Person()
   ARGUMENTS:  none
   RETURNS:    none
   NOTES:      this is the Person() constructor
****************************************************************/
template <class T>
Person<T>::Person()
{
}

/****************************************************************
   FUNCTION:   ~Person()
   ARGUMENTS:  none
   RETURNS:    none
   NOTES:      this is the Person destructor
****************************************************************/  
template <class T>  
Person<T>::~Person()
{
}

/****************************************************************
   FUNCTION:   setFirstName(const string &x)
   ARGUMENTS:  const string &x - the first name of student
   RETURNS:    none
   NOTES:      this function sets the students first name
****************************************************************/
template <class T>
void Person<T>::setFirstName(T &x)
{
     firstName = x;
}

/****************************************************************
   FUNCTION:   getFirstname() const
   ARGUMENTS:  none
   RETURNS:    string firstName
   NOTES:      this function returns the students first name
****************************************************************/
template <class T>
T Person<T>::getFirstName() const 
{
     return firstName;
}
...//more functions, but lots of space used... you could comment out the functions methods in the class definition if you wanted to try compiling?!

I hope someone sees an obvious mistake i am overlooking. My textbooks and previous projects all seem to be similar to what i have done on this...yet they seemed to work!

Thanks again folks

[Freaky_Chris]

Whats the exact error, thats the easiest way :)

Chris

[tones1986]

[Linker error] undefined reference to `Person::setFirstName(std::string&)'
[Linker error] undefined reference to `Person::setLastName(std::string&)'
[Linker error] undefined reference to `Person::setSSN(std::string&)'
... and the same for each function listed in the class...

So not really an 'error' but a linker error...thanks!!!

***EDIT***

I just edited my variables in the class definition to be of type T...

private:
      T firstName;
      T lastName;
      T SSN;
      T DOB;
      T gender;

Thinking that might be it...but no go there... is it something else? Cheers for helping all.

[StuXYZ]

That looks like an error in getting an appropiate type built.
That can occur when you have multiple files. (compile+compiler flag dependent)

Add a template instanciation template class person<std::string>; at the end of person.cpp and if we are lucky it will fix/change the problem.

Note: If that is the problem, then expect a lot of compiler errors in person since you will not have actually compiled any instance of person yet.

[tones1986]

StuXYZ --- thank you for your effort, i tried you above mentioned idea, and that did not work! (thank you for trying/helping though!) Soooo....

I am going to upload all files of my code. I realize thats a pain in the so and so... but for people to see exactly what im doing and how i am getting errors, it might help seeing all appropriate files for your own tests/compiling.

Thanks for your patience and time.

***EDIT****

After editing my student.h and student.cpp files... to use templates... i get ONE error...so i might be getting somewhere. I think you were right to mention that the error could be caused by using multiple files/templates.

So here is my new error:

23 C:\Users\Tony\Documents\Spring 2009\CSCI 340\Project 2\Student.h expected class-name before '{' token

On this line:

template <class T>
class Student : public Person {
	public:

I will re-upload my Student.h and Student.cpp so that changes can be seen etc.

Thanks a ton.

[StuXYZ]

You have some errors: ALL of which should have been explained by you compiler, that you can get to linking is just telling you to get a better compiler (gcc is the minimum and free.).
(a) to (c) stop your code compiling/linking.

(a) student inherrits from Person BUT person is a template class so
which person is student inherriting from e.g. Person<int> Person<std::string> ????

(b) Put the line given in my last post at the bottom of Person.cpp

(c) You cant use Person:: in print_info (student) , so get rid of it, just getFirstName() etc.
[well you can use Person<std::string> or whatever you decided on Student to inherrit from,
but that will give you an unnecessary dependence on your template choise.]

(d) Fixed size array of courseInfo looks bad.

(e) return const references for strings in the getGrade() etc.

(f) void CourseInfo::incrementCount(int &x) {x = x + 1;} This HAS to be wrong!! (I did lol at this!)

(g) Grade/year as strings???

(h) Add some checking etc.

Those threefixes (a-c) get it to compile and link.

Adding your functionallity is another story.

[programmerkk]

can a template class of person be made????

[programmerkk]

can we make a person template class
plx explain ur reasons