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Fiber Optic
Guest
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 Posted: Thu Jul 28, 2005 3:08 am Post subject: friend function of templated class |
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I wrote a sample app to test using a function to obtain friend-level
access to a templated class. However, I am getting similar errors from
two separate compilers.
If anyone can recommend what function f1() should look like in order
to get it to work I would appreciate it.
Output and code follows.
Chris
$ g++ --version
g++ (GCC) 3.3.1 (cygming special)
$ g++ template.cpp -Wno-non-template-friend
/cygdrive/c/DOCUME~1/<name>/LOCALS~1/Temp/cchYWCO0.o(.text+0x7e):template.
cpp: undefined reference to `f1(Stuff<int, (int)14>&)'
collect2: ld returned 1 exit status
Microsoft Visual Studio .NET 2003
template1 error LNK2019: unresolved external symbol "void __cdecl
f1(class Stuff<int,14> &)" (?f1@@YAXAAV?$Stuff@H$0O@@@@Z) referenced in
function _main
#include <iostream>
using namespace std;
template<class T, int elements> class Stuff;
template<class T, int elements>
void __cdecl f1(Stuff<int, 14> &stuff)
{
cout << "f1() size is " << stuff.size << endl;
}
template
class Stuff
{
friend void f1(Stuff<T, elements> &stuff);
public:
Stuff();
int getSize() { return size; }
private:
int size;
};
template<class T, int elements>
Stuff <T, elements>::Stuff()
{
size = elements;
cout << "In Stuff(" << elements << ")" << endl;
}
int main(int argc, char* argv[])
{
Stuff
cout << "Stuff size is " << stuff.getSize() << endl;
f1(stuff);
return 0;
}
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Ian
Guest
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| Posted: Thu Jul 28, 2005 3:39 am Post subject: Re: friend function of templated class |
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Fiber Optic wrote:
| Quote: | I wrote a sample app to test using a function to obtain friend-level
access to a templated class. However, I am getting similar errors from
two separate compilers.
If anyone can recommend what function f1() should look like in order
to get it to work I would appreciate it.
Output and code follows.
Chris
$ g++ --version
g++ (GCC) 3.3.1 (cygming special)
$ g++ template.cpp -Wno-non-template-friend
/cygdrive/c/DOCUME~1/<name>/LOCALS~1/Temp/cchYWCO0.o(.text+0x7e):template.
cpp: undefined reference to `f1(Stuff<int, (int)14>&)'
collect2: ld returned 1 exit status
Microsoft Visual Studio .NET 2003
template1 error LNK2019: unresolved external symbol "void __cdecl
f1(class Stuff<int,14> &)" (?f1@@YAXAAV?$Stuff@H$0O@@@@Z) referenced in
function _main
#include <iostream
using namespace std;
template
template<class T, int elements
void __cdecl f1(Stuff
try |
void f1(Stuff<T, elements> &stuff)
| Quote: | {
cout << "f1() size is " << stuff.size << endl;
}
template
class Stuff
{
friend void f1(Stuff
try |
friend void f1<T, elements>(Stuff &stuff);
Ian
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Victor Bazarov
Guest
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| Posted: Thu Jul 28, 2005 3:40 am Post subject: Re: friend function of templated class |
|
|
Fiber Optic wrote:
| Quote: | I wrote a sample app to test using a function to obtain friend-level
access to a templated class. However, I am getting similar errors from
two separate compilers.
If anyone can recommend what function f1() should look like in order
to get it to work I would appreciate it.
[..]
#include <iostream
using namespace std;
template
template<class T, int elements
|
Drop the line above. The 'f1' you're defining here is not a template.
| Quote: | void __cdecl f1(Stuff
{
cout << "f1() size is " << stuff.size << endl;
|
You cannot use 'stuff' here since 'Stuff' hasn't been defined. The body
of this function should be moved below.
| Quote: | }
template
class Stuff
{
friend void f1(Stuff
|
Here you're declaring 'f1' as a non-template function.
| Quote: | public:
Stuff();
int getSize() { return size; }
private:
int size;
};
template<class T, int elements
Stuff
{
size = elements;
cout << "In Stuff(" << elements << ")" << endl;
}
int main(int argc, char* argv[])
{
Stuff
cout << "Stuff size is " << stuff.getSize() << endl;
f1(stuff);
return 0;
}
|
This should compile:
----------------------------------------------------
#include
using namespace std;
template<class T, int elements> class Stuff;
void f1(Stuff<int, 14> &stuff);
template<class T, int elements>
class Stuff
{
friend void f1(Stuff<T, elements> &stuff);
public:
Stuff();
int getSize() { return size; }
private:
int size;
};
template<class T, int elements>
Stuff <T, elements>::Stuff()
{
size = elements;
cout << "In Stuff(" << elements << ")" << endl;
}
void f1(Stuff
{
cout << "f1() size is " << stuff.size << endl;
}
int main(int argc, char* argv[])
{
Stuff
cout << "Stuff size is " << stuff.getSize() << endl;
f1(stuff);
return 0;
}
----------------------------------------------------
If it doesn't, post the error messages.
V
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Fiber Optic
Guest
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| Posted: Thu Jul 28, 2005 5:26 am Post subject: Re: friend function of templated class |
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Thanks Victor. It compiles just fine.
-Chris
Victor Bazarov wrote:
| Quote: | Fiber Optic wrote:
I wrote a sample app to test using a function to obtain friend-level
access to a templated class. However, I am getting similar errors from
two separate compilers.
If anyone can recommend what function f1() should look like in order
to get it to work I would appreciate it.
[..]
#include <iostream
using namespace std;
template
template<class T, int elements
Drop the line above. The 'f1' you're defining here is not a template.
void __cdecl f1(Stuff
{
cout << "f1() size is " << stuff.size << endl;
You cannot use 'stuff' here since 'Stuff' hasn't been defined. The body
of this function should be moved below.
}
template
class Stuff
{
friend void f1(Stuff
Here you're declaring 'f1' as a non-template function.
public:
Stuff();
int getSize() { return size; }
private:
int size;
};
template<class T, int elements
Stuff
{
size = elements;
cout << "In Stuff(" << elements << ")" << endl;
}
int main(int argc, char* argv[])
{
Stuff
cout << "Stuff size is " << stuff.getSize() << endl;
f1(stuff);
return 0;
}
This should compile:
----------------------------------------------------
#include
using namespace std;
template
void f1(Stuff<int, 14> &stuff);
template<class T, int elements
class Stuff
{
friend void f1(Stuff
public:
Stuff();
int getSize() { return size; }
private:
int size;
};
template<class T, int elements
Stuff
{
size = elements;
cout << "In Stuff(" << elements << ")" << endl;
}
void f1(Stuff
{
cout << "f1() size is " << stuff.size << endl;
}
int main(int argc, char* argv[])
{
Stuff
cout << "Stuff size is " << stuff.getSize() << endl;
f1(stuff);
return 0;
}
----------------------------------------------------
If it doesn't, post the error messages.
V
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