3 replies to this topic

[RaiDK]

Doing a uni assignment atm and getting a really weird bug:

Error 1 error LNK2001: unresolved external symbol "public: virtual void __thiscall Student::DisplayInformation(void)" (?DisplayInformation@Student@@UAEXXZ) Student.obj Assignment 1 Remake

Error 2 error LNK2001: unresolved external symbol "public: virtual void __thiscall Student::DisplayAssessment(void)" (?DisplayAssessment@Student@@UAEXXZ) Student.obj Assignment 1 Remake

Guilty code is as following:

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

class Student
{
public:
    Student();

*snip*

[b]    virtual void DisplayInformation();
    virtual void DisplayAssessment();[/b]
    
private:
*snip*
    
};

When I comment out the virtual functions it works fine though. No clue how to solve this one

Edited by RaiDK, 25 March 2009 - 05:08.

[CodeCat]

Unresolved references mean that there are calls to a function, but the function itself isn't implemented anywhere. Are those functions actually defined in a .cpp file somewhere? If not, then perhaps you intended to make the functions abstract (pure virtual)?

[RaiDK]

Ah yep, that was the problem... They weren't in the CPP file yet. I'd assumed the error was elsewhere since it compiled fine with regular methods not being in the CPP :-S

Thanks for your help, you knew more on the subject than the subject lecturer did

[CodeCat]

Like I said, you only get undefined reference errors if there are actually references to a function. So as long as you don't call the function anywhere, there won't be an error if the function is not implemented. Perhaps that's what happened first time: You added a function call and this triggered the error.