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When is delete called?

Started by Aargyle Apr 24, 2003 at 10:28 AM 2 replies 200+ views

Original Post

Apr 24, 2003 at 10:28 AM

I was curious how the scope destruction of objects interacts with constructors and destructors, and new and delete. The situation I am thinking of is this: class a { B* b; } a::a() { b = new B(); } a::~a() { delete b } Now, when the constructor is called memory is allocated, but doesn't this get destroyed when it goes out of scope? If not, does dynamically allocated memory ever get destroyed by leaving scope? And also, if scope doesn't call delete, will the OS *ever* call delete on anything without me specifically calling it? Thanks

[edited by - aargyle on April 24, 2003 11:33:46 AM]

Qw3r7yU10p!

Apr 24, 2003 at 10:39 AM

      
{ //beginning of scope

    a test; //calls a::a() and creates an object of type 'a' called 'test'

} // end of scope a::~a() is called

// 'test' doesn't exist any more and is unknown to the compiler

when a::a() is called it calls new B(); which calls B::B()
when a::~a() is called is calls delete b; which calls B::~B()

[edited by - petewood on April 24, 2003 11:40:29 AM]

owl

267

owl

Apr 24, 2003 at 10:46 AM

quote:
Original post by Aargyle
doesn''t this get destroyed when it goes out of scope?

nope. The scope of b is the a instance, not the a contructor.

Aargyle

Author

Aargyle

Apr 24, 2003 at 10:54 AM

Perfect thanks

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