Comments on: delete, operator delete() and NULL pointers https://codesynthesis.com/~boris/blog//2008/11/17/delete-and-null-pointers/ Boris Kolpackov's blog about software Tue, 07 Apr 2026 09:02:29 +0000 http://wordpress.org/?v=2.2.2 By: Boris Kolpackov https://codesynthesis.com/~boris/blog//2008/11/17/delete-and-null-pointers/#comment-546 Boris Kolpackov Tue, 09 Dec 2008 03:39:59 +0000 https://codesynthesis.com/~boris/blog//2008/11/17/delete-and-null-pointers/#comment-546 Francesco, You can use one either depending on the semantics of the code. If you are allocating a "type-less" memory block then using operator new()/delete() might be a good idea to convey this. On the other hand, if you are allocating an array of some objects then using the new/delete expressions is a more straightforward way. In some cases, like in the buffer example above, you can reasonably use either one. As for how to detect the performance penalty, one would normally use a profiler. I use oprofile on GNU/Linux. If operator delete() is called very often, the profiler output will show that. The point in knowing the difference between the delete-expression and operator delete() before profiling is that you may be implementing a library, for example a memory buffer, that other applications will use. And you cannot predict what other applications will do with it. Some may construct and destroy a lot of empty buffers. Boris Francesco,

You can use one either depending on the semantics of the code. If you are allocating a “type-less” memory block then using operator new()/delete() might be a good idea to convey this. On the other hand, if you are allocating an array of some objects then using the new/delete expressions is a more straightforward way. In some cases, like in the buffer example above, you can reasonably use either one.

As for how to detect the performance penalty, one would normally use a profiler. I use oprofile on GNU/Linux. If operator delete() is called very often, the profiler output will show that. The point in knowing the difference between the delete-expression and operator delete() before profiling is that you may be implementing a library, for example a memory buffer, that other applications will use. And you cannot predict what other applications will do with it. Some may construct and destroy a lot of empty buffers.

Boris

]]> By: Francesco https://codesynthesis.com/~boris/blog//2008/11/17/delete-and-null-pointers/#comment-544 Francesco Mon, 08 Dec 2008 15:37:04 +0000 https://codesynthesis.com/~boris/blog//2008/11/17/delete-and-null-pointers/#comment-544 Hi Boris, I found your blog today, I was looking for information about rvalue references. I will study your two posts about them, but in the meanwhile I would like to ask you a question about this post. First of all, the conclusion appears to me that it's better to use the first form (delete expression) rather than the second (operator delete): by checking earlier we avoid the unneeded call. Am I right? The second question is more general: How can you obtain a reliable measure if this subtle modification really makes a difference in an existing program? This is not something that you can test with a simple snippet. What kind of profiling tool/technique do you suggest for such a measurement? Thanks in advance, Francesco Hi Boris,
I found your blog today, I was looking for information about rvalue references. I will study your two posts about them, but in the meanwhile I would like to ask you a question about this post.

First of all, the conclusion appears to me that it’s better to use the first form (delete expression) rather than the second (operator delete): by checking earlier we avoid the unneeded call. Am I right?

The second question is more general: How can you obtain a reliable measure if this subtle modification really makes a difference in an existing program? This is not something that you can test with a simple snippet. What kind of profiling tool/technique do you suggest for such a measurement?

Thanks in advance,
Francesco

]]>