What's the Difference Between `delete` and `delete[]` in C ?

Understanding the Distinction between delete and delete[] Operators

In C , the delete and delete[] operators play crucial roles in memory management. However, there is a common misconception regarding their equivalence. To clarify this, let's explore the differences between these operators.

delete_vs_delete[]

The delete operator is specifically used to deallocate single objects allocated using the new operator. Attempting to use delete on an array is undefined behavior and can lead to unexpected program crashes.

On the other hand, the delete[] operator is designed to deallocate arrays that were allocated using the new[] operator. Using delete[] on a single object is also undefined behavior.

Confirmation from the Standard

According to the C standard (5.3.5/2), "In the first alternative (delete object), ... If not, the behavior is undefined." This makes it clear that using delete on an array is not allowed. Similarly, "In the second alternative (delete array), ... If not, the behavior is undefined." confirms that using delete[] on a single object is also forbidden.

Conclusion

Contrary to popular belief, delete and delete[] are not equivalent operators. Using them incorrectly can lead to unpredictable program behavior. Always remember to use delete for single objects and delete[] for arrays to ensure proper memory management and avoid undefined behavior.

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