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Tip of the Day
Language: C++
Expertise: All
Feb 11, 2000



Building the Right Environment to Support AI, Machine Learning and Deep Learning

Heap or Free-Store?

The terms heap and free-store are used interchangeably when referring to dynamically allocated objects. Are there any differences between the two?

Technically, free-store is an abstract term referring to unused memory that is available for dynamic allocations. Heap is the data model used by virtually all C++ compilers to implement the free-store. In practice, however, the distinction between heap and free-store is roughly equivalent to the differences between the memory models of C and C++, respectively. In C, you allocate memory dynamically using malloc(), and release the allocated memory using free(). The allocated memory is not initialized. Dynamic allocations in C are said to take place on the heap. In C++, you perform dynamic allocations with new and release the allocated memory with delete. Operator new automatically initializes the allocated memory (by calling the object's constructor), and delete automatically destroys the object before releasing its memory. In C++, dynamic allocations are said to take place on the free-store.

Note that the heap and free-store may reside on distinct physical memory regions and they might be controlled by different underlying memory managers.

Danny Kalev
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