Class instance within another class?

**FlyingIsFun1217** · 12-04-2009

Hey

I have a somewhat interesting situation / question. Let's say I had a class that was meant for database manipulation with the following code:

Code:

#include <iostream>

using namespace std;

SQL::database testDB("test.db");

testDB << "SQL operation";

And let's say I'm making a class of my own, in which I want to use an instance of SQL::database, just like I would in my main program.

More specifically, I'm wondering if there's a way to create an instance of SQL::database as a private member of my own class, so that my classes functions can each reference to the instance.

Thanks for the help, hope I was clear in my point!

FlyingIsFun1217

**bithub** · 12-04-2009

Of course:

Code:

class MyClass
{
public:
    MyClass(void) : testDB("test.db") {}
    void foo(void) { testDB << "SQL operation"; }

private:
    SQL::database testDB;
};

**FlyingIsFun1217** · 12-04-2009

Sweet! What is the term for this? I wouldn't mind reading up on it more.

Thanks!

**bithub** · 12-04-2009

Originally Posted by FlyingIsFun1217

Sweet! What is the term for this? I wouldn't mind reading up on it more.

Thanks!

Composition

**FlyingIsFun1217** · 12-04-2009

Thanks again! Something I love about the community here, always seems to be willing to help.

FlyingIsFun1217

**VirtualAce** · 12-05-2009

You could also use aggregation since the SQL database lifetime probably would not be controlled by the objects using it.

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