Cast to interface and check for null vs checking with "is" right away: What is best and why? There are two alternatives I am considering as guard clauses to only allow some code to run if I have an object of proper type:  var targetObject = eventArgs.Value as MagicType;  if (targetObject != null) {     DoStuffWith(targetObject); }   or else:  if (targetObject is MagicType) {      // DoStuffWith(targetObject);  // not quite. Actually:      DoStuffWith((MagicType)targetObject); }   Looking at both alternatives, they seem pretty equivalent, but I know the operations (as vs is) are conceptually different.  So the question is: which one should be preferred? Is that choice dependent on scenario? And why?
Casting vs using the 'as' keyword in the CLR When programming interfaces, I've found I'm doing a lot of casting or object type conversion.  Is there a difference between these two methods of conversion?  If so, is there a cost difference or how does this affect my program?  public interface IMyInterface {     void AMethod(); }  public class MyClass : IMyInterface {     public void AMethod()     {        //Do work     }      // Other helper methods.... }  public class Implementation {     IMyInterface _MyObj;     MyClass _myCls1;     MyClass _myCls2;      public Implementation()     {         _MyObj = new MyClass();          // What is the difference here:         _myCls1 = (MyClass)_MyObj;         _myCls2 = (_MyObj as MyClass);     } }   Also, what is "in general" the preferred method?
Solving "mv: Argument list too long"? I have a folder with more than a million files that needs sorting, but I can't really do anything because mv outputs this message all the time  -bash: /bin/mv: Argument list too long   I'm using this command to move extension-less files:  mv -- !(*.jpg|*.png|*.bmp) targetdir/ GNU find and masking the {} for some shells - which? The man page for GNU find states:    -exec command ;     [...] The  string `{}'  is  replaced  by the current      file name being processed everywhere it occurs in the      arguments to the command, not just in arguments where      it is alone, as in some  versions  of  find.     Both  of  these  constructions might need to be escaped      (with a `\') or quoted to protect them from expansion      by the shell.     That's from the man to find (GNU findutils) 4.4.2.   Now I tested this with bash and dash, and both don't need to have the {} being masked. Here is a simple test:  find /etc -name "hosts" -exec md5sum {} \;    Is there a shell, for which I really need to mask the braces? Note, that it doesn't depend upon whether the file found contains a blank (invoked from bash):   find ~ -maxdepth 1 -type d -name "U*" -exec ls -d {} \;  /home/stefan/Ubuntu One   This changes if the found file is passed to a subshell:  find ~ -maxdepth 3 -type d -name "U*" -exec bash -c 'ls -d {}' \;  ls: cannot access /home/stefan/Ubuntu: No such file or directory ls: cannot access One: No such file or directory   which can be solved by:  find ~ -maxdepth 3 -type d -name "U*" -exec bash -c 'ls -d "$0"' {} \;   in contrast to:   find ~ -maxdepth 3 -type d -name "U*" -exec bash -c 'ls -d "{}"' \;  /home/stefan/Ubuntu One   but that's not what the man page is talking about, is it? So which shell treats {} in a different way? For the past couple of weeks, a process identified as usernoted appeared to "take over" my machine after a few hours of use, eating over 99% of available CPU.  Force quitting the process doesn't help; only a system restart puts usernoted to sleep for a while.  What is this process and how do I get it under control?  I am running OS X 10.10.5 (build 14F1021). The title of  of  is, "Is it posible [sic]?"  This doesn't provide any information at all. It should be mandatory for everyone asking questions on the Internet to read , which says:     Help your community learn from the question. When you field a good question, ask yourself "How would the relevant documentation or FAQ have to change so that nobody has to answer this again?" Geometric proof for irrationality of $\pi$ Is there a geometric proof for irrationality of $\pi$? That would be neat. Is it possible to take an image from the clipboard and output it to a file (using X)?  I can do this with text easily:  $ xclip -selection c -o &gt; file.text   But when I try the above with an image nothing is written.    The reason I want to do this is I don't have an image editor installed, and it got me thinking whether I could do this without installing one. How do I calculate CRC32 of a string How do I calculate the CRC32 (Cyclic Redundancy Checksum) of a string in .NET? My teacher told me that two parallel lines have a point of intersection, it is called Point at infinity. But I I can't understand how it can be true or how was it proved, can someone explain this to me?  Thank you. How do I create a file and mount it as a filesystem? How do I create a file of size 10M, format it with ext3 filesystem and then mount it in /media/fuse?  I tried with  mkfs -t ext3 file   then to mount it  mount -t ext3 file /media/fuse   It didn't work because it said that file wasn't a block device. Can anybody help me? Prove that $\gcd(a^n - 1, a^m - 1) = a^{\gcd(n, m)} - 1$ For all $a, m, n \in \mathbb{Z}^+$,   $$\gcd(a^n - 1, a^m - 1) = a^{\gcd(n, m)} - 1$$ Parallel universes: are there an infinite amount of universes? Parallel universe: in every universe, you are presented with a different decision. Does that mean there are an infinite amount of parallel universes? I.e., if in one universe I choose to go left, I am then presented with different choices vs if i choose right, and that creates more universes with more decisions to be made.  Or does it mean that in the end of one's life we end up in the same place, meaning that its just one parallel universe that eventually collides with the other. What are the consequences of a US citizen overstaying a Schengen visa? For every generation of Excel I can remember (including 2010, which I'm using now), Excel's "Auto Size Row" features sometimes fails to actually auto size a row when the cell contains wrapped text. When it works properly, all the text is revealed and there is no additional space below the last line of text. When it fails, it adds extra space below the text. To make matters worse, what you see is not always what you get, i.e., text that appeared okay on screen gets cut off when it's printed. You also get different sizing depending on whether you are zoomed in/out or at actual size.  Simple test case:  Why is there a one-line gap after the text in cell A1 but not in A2?  (To reproduce: set width of column A to 17.14 (125 pixels), text wrap on, and cell alignment top.)  (I double-checked that I applied Auto Fit Row Height to both rows. Zoom level is 100%.)    Is there any known remedy for this without resorting to manually adjusting the row heights (which is not practical for more than a handful of rows)? Why sometimes evidence is said to be too complex to compute and other times is negelected cause it is fixed? Say for a game with irregular hotspots (say Risk, or a strategy game like Paradox's Hearts of Iron or Crusader Kings), how do you   Define a non-rectangular hotspot of irregular shape (much like a territory on a map?), in code? What tool can you use to trace out the hotspot and import into your game? What is the algorithm for detecting if someone has clicked within such a hotspot? I'm new to ArcGIS 10 and am trying to do a really simple field calculator equation and it is not working. I'm just trying to find the percentage of a certain demographic trait by doing:  [asian]/[total]*100   It is populating about 10% of the column correctly and then I get an error:     There was a failure during processing, check the Geoprocessing Results   window for details   Obviously my syntax is not incorrect or else it wouldn't start populating the field correctly.   Does anyone have any idea why this is happening? I'm including \usepackage{hyperref} so that each instance of \ref (as well as each page number in the index and the table of contents) automatically links to that page.  When I'm viewing the document (in ) and I click a link, I jump to the linked page.  Is there any easy way to go "back" to where I was before I clicked the link?  (And is the answer any different when using Adobe Acrobat reader?) The currently proposed Gravitational wave detection apparatus consists of Michelson Interferometer which is supposed to measure distances of the order of $10^{-22}$m. But the wavelength of the light used is in the order of micrometers ($10^{-6}$m). How is this possible? The conventional way to measure distance is by counting the interference fringes. But for path difference smaller than wavelength of laser light this is not possible. How is Cycles different from Blender Internal? How does Cycles work and how is it different from Blender Internal?  Which is better? Why are there humans in the Star Wars Universe? Kind of brought to my attention by .  The poster mentions non-humans, which implies that there are humans in the Star Wars universe.  However, since it happened "A long time ago, in a galaxy far far away", how could there be any humans in the Star Wars universe?  Are there "humans" in Star Wars there just because it was easier to make the movies that way?  Other shows such as Star Trek are about the future of humans, so it's easy to understand the existence of humans in those storylines.  However for Star Wars it just doesn't make sense.  It also seems odd that they'd go around creating all these different species and then just leave the main characters as humans. I guess another possibility is that the humans in star Wars eventually populated Earth, but then what happened to all the technology?