Undefined reference error

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C++

//XX.h
template <class T> class XX
{
public:
  XX();
  ~XX();
  static T* get() {//def}
  static void set(T* data){//def}
  static void init();
 private:
  static T *data;
};

//XX.C
template <class T> T* XX<T>::data = 0;
template <class T> 
void XX<T>::init()
{
  data = 0;
}

//Test.h
#include <XX.h>
class Sample{
public:
static void someFunc(int *x){XX<int>::set(x);}
};

//Test.C
int main()
{
int x = 100;
Sample::someFunc(&x);
return 0;
}

This is sample piece of code from my app, i am getting undefined reference error for XX<int>::data and XX<int>init() both. Can anybody help me resolve this error. Thanks in advance!!

Posted 26-Feb-13 0:43am

Member 8576081

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Member 8576081 27-Feb-13 1:06am

Thanks everyone for your response!!!

3 solutions

Solution 2

your syntax error is here

C++

//XX.h
template <class t=""> class XX
{
public:
  XX();
  ~XX();
  static T* get() {//def} //here
  //solution
  static T* get() {}//def
  static void set(T* data){//def} //here
  static void init();
 private:
  static T *data;
};
 
</class>

Posted 26-Feb-13 1:18am

Mohibur Rashid

Solution 3

Obviously you have not defined the construtor and destructor of class XX<t> anywhere.

Either remove the declaration, which will then lead to the generation of default constructors/destructor. Or define the function somewhere.

Posted 26-Feb-13 1:19am

nv3

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Stefan_Lang · Accepted Answer · 2013-02-26T01:16:00

You can't move template code into a C file - it must be in the header file! Or at least it must be accessible from the file that uses this class (so you could in theory include the .c file along with the .h file)

The reason is that the class will be compiled only when the template gets instantiated, and at that point the file that instantiates it must have access to the full implementation.