Does this file required an #include to define FooType? The function's type signature returns FooType* but the function implementation doesn't use FooType.  // test.cpp class FooType;  // Unresolved forward declaration  FooType* GetFoo() { return nullptr; }   It builds without warnings using g++ --std=c++11 -Wall. So is this a legal use of forward declaration?
I am looking for the definition of when I am allowed to do forward declaration of a class in another class's header file:  Am I allowed to do it for a base class, for a class held as a member, for a class passed to member function by reference, etc. ?
I have observed that in gedit if I edit a file, another file is created in the same directory (the one with the same filename and a tilde '~' suffix). The extra file remains even if I close gedit.  I understand the need for a temp file (eg. in case of a crash), but vim for example deletes the extra file it creates, when I close it.  Is there a way to do the same with gedit? Some configuration perhaps? How can I list the contents of a .zip folder in c#? I loved the keyboard shortcuts in Windows 7 (i.e. Win + &larr; moves a window to the left side of the screen), but I'm not sure on what some of the new ones might be for Windows 8.  What are all of the NEW keyboard shortcuts that I can use while working in Windows 8? Abelian quotient group I'm stuck on the following practice problem.   Any hints would be appreciated.  Suppose $N$ is a normal subgroup of  $G$ such that every subgroup of $N$ is normal in $G$ and $C_{G}(N) \subset N$. Prove that $G/N$ is abelian.  I'm not sure how to use the fact that $C_{G}(N) \subset N$.  Thanks Natural Sort Order in C# Anyone have a good resource or provide a sample of a natural order sort in C# for an FileInfo array?  I am implementing the IComparer interface in my sorts. How to run updmap-sys after installing cm-super? My original question was:   The answer that seems suitable to my cause is to install cm-super. I did that (using package manager [winxp 32 bit, MikTex installation 2.9 recently updated]). But still the command  \usepackage{cm-super}    yields an error.  User H Cavendish suggested to run updmap-sys, but I am not sure about how to do that on WinXP.   2011 November 04 edit: I made it sure that I have installed 'cm-super' - but still get the same error:   I have also tried updating the file name databases - but no avail. Why don’t photons interact with the Higgs field and hence remain massless? How to add tags to files in Windows 7 so that they appear in search results In Windows 7, I want to add tags to my files (PDF, Word, Images etc) so that they appear directly in the search results, regardless of their content, title etc.    shows how to search by tag, but it does not tell how to add a tag in any file.  In the long term, I'm planning to add such tags programmatically as well. How many triples $(x,y,n)$ are there such that $x^n - y^n = 2^{100}$ Check if partition is encrypted Correct position of "only" Which is grammatically correct?  I can only do so much in this time.  or  I can do only so much in this time. Why do the directories /home, /usr, /var, etc. all have the same inode number (2)? Can I uninstall and reinstall Ubuntu Software Center? How to prove that $\lim_{n\rightarrow \infty}\frac {n^{2}}{2^{n}}=0$ & $\lim_{n\rightarrow \infty}\frac {n^{2}}{n!}=0$? So this has puzzled me for many a year... I still am no closer to coming to a conclusion, after many arguments that is. I don't think it can, others 100% think it will.   If you have a plane trying to take off whilst on a tread mill which will run at the same speed as whatever the planes tires rotation speed is will it take off?  [edited to be more clear]  The question is simple. Will a plane take off if you put this plane onto a treadmill that will match whatever speed the plane wheels are moving at. So the plane should not be able to move.  This is a hypothetical situation of course. But I am very interested. Possible point location algorithm I need to calculate possible point location based on its speed and some other factors. For example, there is a man in the middle of the forest and I need to calculate his possible location at some time periods. There are few facts about his movement:   His speed differs at certain periods of time - it can be raining, or it can be super hot - speed lowers / increases; Some objects in space - swamps, rocks - can lower his speed as well; At some time periods the man does not move at all.   So, here is the question - is there any algorithm that can calculate possible location of the man based on following parameters? The output should be a polygon for every given time_period.  {   time_periods: [{     from: 2012-12-12T20:00:00,     to: 2012-12-12T22:00:00,     speed: 5   }, {}],   objects: [{     geodata: POLYGON(...),     speed_modifier: 0.5   }, {}] }   Generated polygons will be visualized on the map afterwards. This question is similar, but not identical to:   Whereas the aforementioned question is about whether the hand’s movement is measured from the hand’s point of view or from the caster’s, this question revolves around the total distance the hand can travel to reach its destination.  To illustrate, let me give an example: Two narrow stone pillars stand next to each other, 10 feet apart. They are several kilometers high and on top of each pillar stands a wizard. One wizard casts Maximillian's Earthen Grasp and lets the hand made from compacted soil rise from the ground on his own pillar. With another action, he wants to move the hand in order to restrain the other wizard, who is within range of 30 feet.  Would the hand retract into his own pillar, then rise again from the ground on the other pillar? Or would the hand move several kilometers down the first pillar, across the floor, then several kilometers up the second pillar? What if both pillars would float in the Astral Plane, without a direct ground-based connection between them?  This might seem like a stupid and unnecessary convoluted question, but lo and behold, something similar happened in one of my games. How can I determine if a used game is pirated? Delete commits from a branch in Git Roman numerals used for ordinals