What's Dynamically Allocated Memory?

[fireflies]

What's Dynamically Allocated Memory? Can someone explain it? The book doesn't say much but just talks about 'new' and 'delete'.

Thanks.

 

[ivar4ever]

dynamically allocated memory is the memory allocated in heap at run-time.

see http://en.wikipedia.org/wiki/Heap_(programming)

In computer science, dynamic memory allocation is the allocation of memory storage for use in a computer program during the runtime of that program. It is a way of distributing ownership of limited memory resources among many pieces of data and code. A dynamically allocated object remains allocated until it is deallocated explicitly, either by the programmer or by a garbage collector; this is notably different from automatic and static memory allocation. It is said that such an object has dynamic lifetime.

The Need:
-------------
It is desirable to dynamically allocate space for variables at runtime. It is wasteful when dealing with array type structures to allocate so much space when declared, eg,
struct client clients[100];
This practice may lead to memory contention or programs crashing. A far better way is to allocate space to clients when needed.
The C programming language allows users to dynamically allocate and deallocate memory when required. The functions that accomplish this are calloc(), which allocates memory to a variable, sizeof, which determines how much memory a specified variable occupies, and free(), which deallocates the memory assigned to a variable back to the system.

hope i am clear
Ivar