CODEWITHSUNDEEP
c++visual-c++
XZ6H
XZ6H

Reputation: 1789

Error defining function outside the class

I'm trying to define a function which returns a pointer to a structure 

#include <iostream> 
using namespace std;
class abc
{
private:
    struct n
    {
        int data;
    };
public:
    n* print();
};

n* abc::print()
{
    n* q = new n;
    q->data = 7;
    return q;
}

When this program is compiled "identifier n is undefined" error is shown. Why does the program compile successfully when the same function abc is defined inside the class ?

Upvotes: 1

Views: 58

Answers (3)

WhiZTiM
WhiZTiM

Reputation: 21576

n is a nested class. You need to qualify it with abc::n.

Note: The name and scope of a class is also a namespace, since n is nested in abc, abc is now like the namespace of n.

Full example:

#include <iostream> 
using namespace std;
class abc
{
private:
    struct n
    {
        int data;
    };
public:
    n* print();
};

abc::n* abc::print()
{
    abc::n* q = new abc::n;
    q->data = 7;
    return q;
}

Upvotes: 5

Some programmer dude
Some programmer dude

Reputation: 409196

Outside of the class there is no n symbol, so you need to fully qualify it like abc::n.

Upvotes: 1

H. Guijt
H. Guijt

Reputation: 3365

Because the returned n, when defined outside the class, has a different scope. You can fix this by prefixing it with the correct scope:

abc::n* abc::print()
{
    n* q = new node;
    q->data = 7;
    return q;
}

Upvotes: 1

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