In C++ NULL expands to 0 or 0L. See this quote from Stroustrup’s FAQ: Should I use NULL or 0? In C++, the definition of NULL is 0, so there is only an aesthetic difference. I prefer to avoid macros, so I use 0. Another problem with NULL is that people sometimes mistakenly believe that … Read more
A simple tcp server I had for serving the flash policy file was causing this. I can now catch the error using a handler:
I’m trying to install memcached with older versions (ex: 1.4.5) but I’m not sure how to do it. brew install memcached installs the latest. I also tried brew install memecached1.4.5 but it didn’t work.
Presumably you mean heap from a memory allocation point of view, not from a data structure point of view (the term has multiple meanings). A very simple explanation is that the heap is the portion of memory where dynamically allocated memory resides (i.e. memory allocated via malloc). Memory allocated from the heap will remain allocated … Read more
This is a char: It can only hold one character! This is a C-string: It can hold multiple characters. Another way to write the above is: The 0 at the end is called the NUL terminator. It denotes the end of a C-string. A char* stores the starting memory location of a C-string.1 For example, … Read more
I am having problems converting this formula V = 4/3 π r^3. I used Math.PI and Math.pow, but I get this error: ‘;’ expected Also, the diameter variable doesn’t work. Is there an error there?
Virtual destructors are useful when you might potentially delete an instance of a derived class through a pointer to base class: Here, you’ll notice that I didn’t declare Base’s destructor to be virtual. Now, let’s have a look at the following snippet: Since Base’s destructor is not virtual and b is a Base* pointing to … Read more
They are absolutely different. Inheritance is an “is-a” relationship. Composition is a “has-a”. You do composition by having an instance of another class C as a field of your class, instead of extending C. A good example where composition would’ve been a lot better than inheritance is java.util.Stack, which currently extends java.util.Vector. This is now … Read more
Deleting a function is a C++11 feature: The common idiom of “prohibiting copying” can now be expressed directly: […] The “delete” mechanism can be used for any function. For example, we can eliminate an undesired conversion like this:
Your variable energies probably has the wrong shape: And that’s what happens if you read columnar data using your approach: Probably you can simply use instead. (P.S. Your code looks like it’s undecided about whether it’s data or elementdata. I’ve assumed it’s simply a typo.)