how does the delete function release the memory?

[=?gb2312?B?wNbA1rTzzOzKpg==?=]

struct elem
{
int a;
int b;
};


elem * p = new elem[20];
delete []p;
//-----will the text above memory leak?

 

[Alan Johnson]

struct elem
{
int a;
int b;
};


elem * p = new elem[20];
delete []p;
//-----will the text above memory leak?

No. That is the correct usage of new[] and delete[]. Are you asking
how delete[] knows how many elements you allocated? That depends on your
implementation, but one possible way is that it allocates a few extra
bytes before the pointer that is returned, in which the number of
elements is stored.

See the FAQ 16.14 for details of this and another method.
http://www.parashift.com/c++-faq-lite/freestore-mgmt.html#faq-16.14