How Does `delete[]` Know the Size of the Array It's Deleting?

How Delete[] Determines Array Size

Allocation and deallocation of memory in C are fundamental to memory management. The operator 'delete[]' is crucial for releasing dynamically allocated arrays from the heap. However, it operates without explicit knowledge of the array's size.

Behind the Scenes: Memory Tracking

When an array is created using 'new[]', it reserves memory on the heap. Notably, this process involves internal bookkeeping by the memory allocator. It maintains a "head" segment just before the allocated memory, containing information about the allocated memory size.

Deallocation Process

When 'delete[]' is invoked, it doesn't require explicit size specification because the allocator can retrieve the necessary information from the head segment. This mechanism ensures accurate and efficient deallocation of the entire array, freeing up the allocated memory accordingly.

Standardization and Implementation

The behavior of 'delete[]' is standardized and enforced by the C language. However, the implementation of the memory allocator, including the specific data structures used to track memory allocation, can vary across compilers and operating systems. The exact representation of the head segment may differ, but the fundamental concept of storing size information for proper deallocation remains consistent.

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