g++ 2.3 & g++4.2

[agoswami]

Hi,
this code was running fine on g++2.3 but getting template mismatch id error on g++
4.2. could anyone point out me reason.

using namespace std;

template<class T>
class node
{
public:
T data;
node *next;
};
template<class T>
class link
{

public:
node<T> *first;
link();
void add_node(T data);
friend ostream& operator<< <T> (ostream &o ,link<T> &link_lst);

};
template<class T>
link<T>::link()
{
first =NULL;
}

//Create node in link list
template<class T>
void link<T>::add_node(T data)
{

node<T> *last;
node<T> *p =new node<T>;

p->data =data;
p->next =NULL;

if(first==NULL)
first=p;

else
{
last=first;
while(last->next!=NULL)
last =last->next;
last->next =p;
}

}
template<class T>
ostream& operator<<(ostream &o,link<T> &link_list)
{
node<T> *last =link_list.first;

while(last !=NULL)
o<<" ---->"<<last->data<<endl;
last=last->next;
}
}

int main()
{
link<int>a;
a.add_node(3);
a.add_node(4);
cout<<a;

}

[PanGalactic]

Please use code tags.

What is the exact error message?

Doesn't line 8ish need to be node<T>* next?

[agoswami]

Sorry for providing incomplete info.. I tried with new program also and got following error. it also same issue which is compilable
in g++ 2.3 but getting error in 4.2

Error:
circular.cpp: In instantiation of ‘circular<int>’:
circular.cpp:69: instantiated from here
circular.cpp:22: error: template-id ‘operator<< <int>’ for ‘std::ostream& operator<<(std::ostream&, circular<int>&)’ does not match any template declaration


Program:

/*
* Circular link list
* */
#include<iostream>
using namespace std;

template<class T>
class node
{
public:
T data;
node<T> *next;
};

template<class T>
class circular
{
public:
circular();
void add_node(T data);
node<T> *first;
friend ostream& operator<< <T>(ostream& o,circular<T>& list);
};

template<class T>
circular<T>::circular()
{
first =NULL;
}

template<class T>
void circular<T>::add_node(T data)
{
node<T> *last;
node<T> *p =new node<T>;

p->data =data;

if(first==NULL)
first=p;

else
{
last =first;
while(last->next!=first)
last=last->next;

p->next;
last->next=p;

first=p;
}
}

template<class T>
ostream& operator << (ostream& o,circular<T>& list)
{
node<T> *last =list.first;

while(last->next!=last)
{
o<<" last--->data "<<last->data;
last =last->next;
}
}

int main()
{
circular<int> c;

for(int i=0;i<5;i++)
c.add_node(i);

cout<<c;

return 0;
}

[moorecm]

In code tags:

/*
* Circular link list
* */
#include<iostream>
using namespace std;

template<class T>
class node
{
public:
T data;
node<T> *next;
};

template<class T>
class circular
{
public:
circular();
void add_node(T data);
node<T> *first;
friend ostream& operator<< <T>(ostream& o,circular<T>& list);
};

template<class T>
circular<T>::circular()
{
first =NULL;
}

template<class T>
void circular<T>::add_node(T data)
{
node<T> *last;
node<T> *p =new node<T>;

p->data =data;

if(first==NULL)
first=p;

else
{
last =first;
while(last->next!=first)
last=last->next;

p->next;
last->next=p;

first=p;
}
}

template<class T>
ostream& operator << (ostream& o,circular<T>& list)
{
node<T> *last =list.first;

while(last->next!=last)
{
o<<" last--->data "<<last->data;
last =last->next;
}
}

int main()
{
circular<int> c;

for(int i=0;i<5;i++)
c.add_node(i);

cout<<c;

return 0;
}

[moorecm]

Try something like (line 22):

template<typename T2>
friend ostream& operator<<(ostream& o,circular<T2>& list);

[agoswami]

thx it is working but could i know the reason why it was not working.....

[moorecm]

It looks like the syntax for template member functions has changed over the years (gcc 2.3 is very old).

[PanGalactic]

I assumed he meant 3.2, not 2.3. gcc 2.3 is 18 years old. http://gcc.gnu.org/releases.html

[agoswami]

ya it is typo mistake