Is `delete ptr;` Equivalent to `delete[] ptr;` for Array Deallocation in C ?

Is delete[] Equivalent to delete?

Consider the C code below:

IP_ADAPTER_INFO *ptr = new IP_ADAPTER_INFO[100];

When attempting to free the allocated memory, one might consider using delete ptr;. However, it's crucial to understand the implications of such an action:

Potential Memory Leak:

Using delete ptr; to free an array allocated with new[] can result in undefined behavior and potential memory leaks. The reason lies in how C manages memory for arrays:

• new[] allocates a contiguous block of memory for an array of objects.
• delete ptr; attempts to deallocate a single object pointed to by ptr.

In our example, ptr points to an array of 100 IP_ADAPTER_INFO objects, not a single object. Attempting to delete a single object instead of the entire array can corrupt memory and cause undefined behavior.

Disassembled Code Comparison:

The disassembly code generated by Visual Studio 2005 highlights the difference between delete ptr; and delete []ptr;:

• delete ptr; calls operator delete, which is meant for single object deletion.
• delete []ptr; calls operator delete[], which is specifically designed for array deletion.

Undefined Behavior:

Using delete ptr; for an array can lead to undefined behavior and is strongly discouraged. It's essential to consistently use new[] for allocation and delete [] for deallocation of arrays to avoid memory leaks and ensure proper memory management.

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