what is the use of static variable in this program   /* program to find the addition of n numbers without using recursion:*/ #include&lt;stdio.h&gt;  int main(){      int n,sum;      printf("Enter the value of n: ");     scanf("%d",&amp;n);      sum = getSum(n);      printf("Sum of n numbers: %d",sum);      return 0; }  int getSum(n){      static int sum=0;      if(n&gt;0){          sum = sum + n;          getSum(n-1);     }      return sum; }
I've seen the word static used in different places in C code; is this like a static function/class in C# (where the implementation is shared across objects)?
Does anyone know whether there are only finitely many of primes of the form $6^{2n}+1$, where $n$ zero or any natural number? When a polished piece of metal (or steel in particular) is heated to incandescence, how do its reflective properties change?  Given a mirror-like surface, would the object temporarily cease to act like a mirror at a certain temperature?  Would the specular reflection of light turn into diffuse reflection; in other words, would the surface temporarily become matte/dull?  I am not asking about permanent changes to the object such as melting, but rather can there be a temporary change in the reflectivity only while the the object is hot, that disappears when the object is cooled down?  Background of the question: I have a laser scanner that usually has trouble scanning shiny surfaces with high specular/ low diffuse reflectivity; and it seems to work a lot better for hot steel pieces than for cold ones. Glowing steel also looks less shiny to me than cold steel, but of course that is hard to tell with all the glowing This is a  about understanding and remediating the Heartbleed security issue.   What exactly is CVE-2014-0160 AKA "Heartbleed"? What is the cause, what OSs and versions of OpenSSL are vulnerable, what are the symptoms, are there any methods to detect a successful exploit?   How can I check to see if my system is affected? How can this vulnerability be mitigated? Should I be concerned that my keys or other private data have been compromised? What other side effects should I be concerned about? How to remove "phone style" Gnome swipe to unlock I need to remove the annoying new "locking" screen that shows a giant clock: I can't remove it with just moving the mouse (as with any other desktop environment), the animation is slow, and it isn't asking me for a password!  I managed to disable it, just to discover that now I can't lock my screen on purpose, so I can't go away from the computer.  Just to clarify, I want to:   After some time the screen could go black, but if I move the mouse or press any key then I can use it directly (like a normal screensaver). If I press super-L then it is locked, and I must type the password to unlock (like a normal lock screen).   I found several "solutions", but none seems to work: How to typeset subscript in usual text mode? I have a sight hosted on .ie domain but it is near the NI(Northern Ireland) border and the business has a lot of NI traffic. So when someone searches in NI with certain key words I would like the site to appear in the results, it currently doesn't.   I have seen this post    But was wondering the best way around this. Would it be to create a .co.uk version that redirects to the .ie site? Or would I have to create a separate .co.uk site?  Any help appreciated thanks. Can I visit Schengen countries on a Type-D Schengen Visa? I’m going to Germany for a semester exchange and I have a long-stay visa from Germany. Can I travel to the other Schengen states during this period with this visa or do I have to apply for a separate short stay Schengen visa?  My visa is German national visa type D. It is for a duration of 4 months, i.e., longer than 90 days. It says on the visa that the long stay visa is valid in Deutschland, which is different from my earlier visa, which I had when I visited Germany earlier; that one was a short stay visa and said it was valid in Schengen Staten.  Perhaps my current visa means that I can stay in Germany for a period of longer that 90 days can visit the other Schengen states if I don’t exceed the 90 day period. Coloring a black and white PDF graphic I have a graphic in PDF format (originally converted from an SVG) that is monochromatic (black on white). Is it possible using TikZ or PSTricks but not (Illustrator or Inkscape) to include this image in a different color?  Example:    While it lasts (there seems to be no long term way to host a pdf), you can .  Edit: Simple was perhaps a bit of a misnomer - the pdfs are cropped and monochromatic, but to intricate to redraw on my own. The above example is a character from a font (which I can recolor), but it gives a good example of what shapes I am talking about. I want to build a flow to trigger an email when a date in one of the fields is nearing. I have a field named Payment due date. is it possible to trigger an email 2 days prior to the Payment due date. So that I don't miss the payment due date and payment is not delayed. Any kind of assistance is appreciated. Thank you very much in advance! How do I find the package that provides a file? What does an icon on the tag mean, for example the "rg" before the sql-server tag as pictured below? I've been wondering about this for a while, since getting interested in knife sharpening.  When using a knife, it will get duller. One (the primary) reason being that you "bend" the edge. You fix this using a honing steel.  After a while though, you need to sharpen the knife again.  Another setting: If you have a brittle knife and/or mistreat your knife you will chip it.   As far as I can tell, this should mean that small pieces of metal (dust, shavings, etc.) come lose, and then likely get in the food.  Is this correct? Are there no health considerations when digesting small pieces of very sharp metal? Set a default parameter value for a JavaScript function I was wondering if anybody knew a command that would allow me to open a Nautilus (if that's the right name for the Ubuntu graphic/window explorer) window from the command line at the current directory that the user is at.  So, if I open a command line, and type:  cd /home/myUser/some/long/path/to/a/directory   Then, I'd like to be able to issue some command:  nautilus open-sesame   And have a graphic window opened to /home/myUser/some/long/path/to/a/directory. Is this even possible? This is a  about Monitoring Software. Also Related:   I need to monitor my servers; what do I need to consider when deciding on a monitoring solution? What do the colors mean in htop? I could not install my modem driver so I have to update and install applications offline. For this I want to use keryx but to install keryx, Python and wxPython have to be installed first. So how do I install Python and wxPython offiline on Ubuntu 13.04?  Note : I don't have internet connection in Ubuntu. So I'll have to download the required file from my Windows 7. I'm looking to create a simple short-lived reservation system, and I'd like to generate confirmation numbers that are   unique random-looking alphanumeric short-ish, at least much shorter than 32 character-long strings returned by sha1   I'm only looking to have ~500 reservations, so I don't imagine high likelyhood of collissions.  One idea I had is generate an sha1 hash based on a date-time stamp and username, then truncating it to its first 10 characters.  Would something like that be reliably unique enough for the purposes of processing ~500 reservations? Is “ ’s ” ever correct for pluralization? A relatively modern dictionary (I don’t know which one, because we’ve cut out the pages and used them as wallpaper in our bathroom, but I know it’s less than 20 years old) indicates that R’s is one correct pluralization of R, as is Rs, but whichever dictionary this is, it’s kind of a no-name brand, so I’m not sure I trust it.  I’ve always wondered what the best way was to pluralize single letters or numerals, like 2’s or 2s.  What’s correct? I've been reading a lot about the oxidative dissimilation etc, and often I see different sources use NADH and NADH2 in the same reactions. One source uses NADH and another uses NADH2 in the exact same way. Is there a difference or is it just a different name for the same substance?