Is There a Real Difference Between the Free Store and Heap in C ?

C : Unveiling the Distinction Between Free-Store and Heap

In the realm of dynamic memory allocation, C offers two primary mechanisms: new/delete and malloc/free. While both are often referred to as operating on the heap, this raises the question of whether there is a practical distinction between the terms "free-store" and "heap."

Is there a clear-cut difference in how compilers handle these terms?

The answer lies in the evolution of C memory management. Historically, the "heap" referred specifically to the memory area managed by the malloc/free functions. However, with the introduction of the new and delete operators, a separate "free-store" concept emerged. This was intended to enforce a separation between the two memory management systems, preventing accidental mixing of different allocators.

Today, for C , the distinction between free-store and heap has become largely conceptual. Both new/delete and malloc/free allocate memory from the same pool, typically managed by the operating system. However, the usage remains distinct. new/delete are used with objects that require constructors and destructors, while malloc/free are more flexible and used for raw memory allocation.

In interviews, it is common to emphasize the traditional distinction:

• "new and delete use the free store, while malloc and free use the heap."
• "new and delete invoke constructors and destructors, unlike malloc and free."

However, interviewers may also acknowledge that modern compilers often do not strictly enforce these distinctions, potentially allowing both operators to access the same memory space.

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