linker error in singleton implementation

[sam_cit]

Hi everyone,

I have the following code and it gives a linker error on MS vc++ 6.0.

error LNK2001: unresolved external symbol "protected: __thiscall
Singleton::Singleton(void)" (??0Singleton@@IAE@XZ)

#include <stdlib.h>

class Singleton
{
public:
static Singleton* Instance();
protected:
Singleton();
Singleton(const Singleton&);
Singleton& operator= (const Singleton&);
private:
static Singleton* pinstance;
};

Singleton* Singleton:instance = 0;

Singleton* Singleton::Instance()
{
pinstance = new Singleton();
return pinstance;
}

int main()
{
Singleton::Instance();
return(0);
}

Can anyone help in this regard?

 

[Kai-Uwe Bux]

Hi everyone,

I have the following code and it gives a linker error on MS vc++ 6.0.

error LNK2001: unresolved external symbol "protected: __thiscall
Singleton::Singleton(void)" (??0Singleton@@IAE@XZ)

#include <stdlib.h>

class Singleton
{
public:
static Singleton* Instance();
protected:
Singleton();
Singleton(const Singleton&);
Singleton& operator= (const Singleton&);
private:
static Singleton* pinstance;
};

Singleton* Singleton:instance = 0;

Singleton* Singleton::Instance()
{
pinstance = new Singleton();

At this point, you attempt to create an instance using the default
constructor. However, that poor guy is not implemented :-(

return pinstance;
}

int main()
{
Singleton::Instance();
return(0);
}

Best

Kai-Uwe Bux

 

[Rolf Magnus]

Hi everyone,

I have the following code and it gives a linker error on MS vc++ 6.0.

error LNK2001: unresolved external symbol "protected: __thiscall
Singleton::Singleton(void)" (??0Singleton@@IAE@XZ)

#include <stdlib.h>

class Singleton
{
public:
static Singleton* Instance();
protected:
Singleton();

Where is the implementation for the above constructor?

 

[=?ISO-8859-1?Q?Erik_Wikstr=F6m?=]

Hi everyone,

I have the following code and it gives a linker error on MS vc++ 6.0.

error LNK2001: unresolved external symbol "protected: __thiscall
Singleton::Singleton(void)" (??0Singleton@@IAE@XZ)

#include <stdlib.h>

class Singleton
{
public:
static Singleton* Instance();
protected:
Singleton();
Singleton(const Singleton&);
Singleton& operator= (const Singleton&);
private:
static Singleton* pinstance;
};

Singleton* Singleton:instance = 0;

Singleton* Singleton::Instance()
{
pinstance = new Singleton();
return pinstance;
}

int main()
{
Singleton::Instance();
return(0);
}

Can anyone help in this regard?

Implement the constructor.

 

[sam_cit]

Implement the constructor.

Thanks everyone, and by the way i was just thinking of moving the
cons, copy cons and operator function to private section, wouldn't
that also server the purpose of singleton implementation?

 

[=?ISO-8859-1?Q?Erik_Wikstr=F6m?=]

Thanks everyone, and by the way i was just thinking of moving the
cons, copy cons and operator function to private section, wouldn't
that also server the purpose of singleton implementation?

Currently there's no real difference between having them protected and
private, you'd still have to implement the constructor. The only
difference would be if you inherit from Singleton, unless you plan to do
that you can have the private.