How Does `delete[]` Know the Size of an Array When Dealing with Pointers?

How Does delete[] Distinguish Arrays from Other Pointers?

In C , the delete[] operator deallocates memory allocated for arrays, but how does it know when a pointer is an array?

Compiler Considerations

Despite the uncertainty in the code you provided, the compiler cannot determine if a pointer points to an array or a single element.

Managed Array Information

Dynamically allocated arrays store additional information beyond the pointer to the first element. This information includes the number of elements in the array.

Delete[] Operation

When delete[] is used on an array pointer, it uses the additional information to:

• Identify that the allocation is an array.
• Deallocate the appropriate number of elements.

Alternative "Delete" Syntax

Some have questioned the need for a separate delete[] syntax since the runtime libraries already manage array size information. However, the original design principle of C sought to minimize overhead for non-array users by avoiding the allocation of additional space for non-array memory blocks.

Delete[] Specificity

Therefore, delete[] is used to explicitly inform the runtime libraries that the allocated memory is an array, enabling them to deallocate it correctly. While this may seem excessive in modern computing, it can still be beneficial in scenarios where memory optimization is critical.

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