Is `delete` Equivalent to `delete[]` for Dynamic Arrays in C ?

Is delete[] Equivalent to delete? An Exploration of Undefined Behavior

The question of whether using delete or delete[] when deallocating a dynamic array can lead to memory leaks has been a subject of debate among programmers. To delve into this topic, let's consider the disassembly code generated by Visual Studio 2005:

; delete ptr;
0041351D mov eax,dword ptr [ptr]
00413520 mov dword ptr [ebp-0ECh],eax
00413526 mov ecx,dword ptr [ebp-0ECh]
0041352C push ecx
0041352D call operator delete (4111DBh)
00413532 add esp,4

; delete []ptr;
00413535 mov eax,dword ptr [ptr]
00413538 mov dword ptr [ebp-0E0h],eax
0041353E mov ecx,dword ptr [ebp-0E0h]
00413544 push ecx
00413545 call operator delete[] (4111E5h)
0041354A add esp,4

Comparing these two blocks of code reveals slight differences in their calls to operator delete and operator delete[]. These distinctions highlight the crucial question: is using delete on a dynamic array equivalent to using delete[]?

The answer to this question, unfortunately, falls under the umbrella of undefined behavior in C . Undefined behavior refers to situations where the behavior of the program is not specified by the language standard. Consequently, it might vary across compilers, compiler versions, and other factors.

Due to this inherent uncertainty, it is strongly advised to avoid using delete on arrays and strictly adhere to using delete[]. This approach ensures predictable behavior and prevents potential memory leaks or other unexpected consequences. In summary, while delete and delete[] may appear similar in certain scenarios, their subtle differences and the potential for undefined behavior demand that programmers use them with caution.

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