NULL POINTER in com.sun.mail.smtp.SMTPTransport.sendMessage
What is a NullPointerException, and how do I fix it?
I've recently decided that I just have to finally learn C/C++, and there is one thing I do not really understand about pointers or more precisely, their definition.  How about these examples:   int* test; int *test; int * test; int* test,test2; int *test,test2; int * test,test2;   Now, to my understanding, the first three cases are all doing the same: Test is not an int, but a pointer to one.  The second set of examples is a bit more tricky. In case 4, both test and test2 will be pointers to an int, whereas in case 5, only test is a pointer, whereas test2 is a "real" int. What about case 6? Same as case 5? How to pronounce fractions with denominators larger than 20 where the last digit of the denominator is 1 or 2? eg 4/31 Disclaimer: I speak British English.  I've noticed a lot of differences between the way Americans and Brits pronounce numbers.1  Since the question concerns this, I thought it might be appropriate to draw attention to it case we inadvertently confuse each other.  My question is not about these differences, I just wish to highlight them in case they cause confusion.  1. You seem to happily call a quarter "a fourth" sometimes, we always call 131 "one hundred and thirty one", we pronounce double digits in phone numbers like 12449 as "one two double four nine", and I think we are much more likely to use expressions like "thirteen hundred" to mean 1300.    Question  When talking about fractions, I have frequently heard  1/2    a half 1/3    a third 1/4    a quarter 1/8    an eighth 1/64   a sixty fourth 1/56   a fifty sixth   etc.  Essentially the rule seems to be that, except for "a whole", "a half", and "a quarter", the word matches the ordinal number; that is to say:      Numeral       Ordinal         Fractional     one           first           whole     two           second          half     three         third           third     four          fourth          quarter     five          fifth           fifth     six           sixth           sixth     fifty-seven   fifty-seventh   fifty-seventh  Even though 1/4 is a quarter, 1/64 is a sixty-fourth.  So what’s 1/62?  A  sixty-twoth?  A sixty-second? Surely not a sixty-half!  I know that simply saying one over sixty-two can usually work, but I'm asking specifically for the word itself, i.e.  if I divide a huge pizza into 21 pieces, what are the pieces?  Other than baker’s twentieths.  Summary: Can anyone point me to any sources (whether style guides or common usage studies or anything else) that discuss the pronunciation of fractions; specifically one that discusses this separately from ordinal numbers, rather than how to form ordinal numbers in the first place. How can I make a fake name when I use command blocks? I'm trying to make a mini game but I want it so that when you press a button over a command block it will say "BOB welcome", so 'bob' instead of the @a or @p sign and then followed by the message. All I know is that I need to use /tellraw. How to restart X Window Server from command line? How can I restart X Window Server from the command line?  I'd really like to be able to restart my GUI without having to do a full system reboot. Last year I hired someone to do some work for our website but accidentally lost the PSD files since then. It's a fairly basic concept but I am fairly inexperienced with using masks.  How can I create the black circular gradient area as shown in this image below? I need to get as close as possible where it matches existing images on the site, why I am hoping its not too hard.  Thank you! How do I access folders created on Ubuntu with Windows? I have an external hard drive on which I back up my files, and I've moved some files from an Ubuntu laptop to it as well. However, I can't find a way to open the folder containing these files with my main Windows 10 laptop. When I try to open the folder "VPC 3 : UBUNTU" (the "VPC" is just a name for the laptop  with no special implications), the following happens:  It responds with "___ is unavailable. Make sure the disk is inserted..." Would this look natural:     StackExchange is a helluva site! I found out about this site at Facebook.    Or should we use the preposition on:     StackExchange is a helluva site! I found out about this site on Facebook.    Or are both okay?   (Inspired by a ) Related to : The question specifies morphs, but I wondered if this was true for Manifest as well? As Manifest is not an ability on the card, does  prevent it from being turned face up for its mana cost? Need help recalling name of sci-if story about earth evolving into electronic life forms Read a story once about earth being abandoned for long periods of time. Upon the return of man to earth all life forms, flora and fauna, have evolved into intricate electronic forms of themselves.   Would like to find that story and it's name. Parsing input with scanf in C How can I pad an integer with zeros on the left? How to write a LaTeX package that bundles not only .sty and .cls files but also some logos in .pdf or .eps formats? I would like to make a LaTeX package with the following subdirs:   tex/latex/common (a common .tex file shared among beamer and letter) tex/latex/resources (lots of pdf and eps files with graphical resources) tex/latex/mybeamer (a custom beamer theme with 5 .sty files) tex/latex/myletter (a .cls file for a letter template)   I would like to package these files into a single LaTeX package that users could install in an easy way. I read about the .ins and .dtx files and I can see how to pack the .sty and .cls files but what about the extra graphics - the resources folder which contains several PDF and .eps files? Alternative methods to prove that $Z_m$ is a field under addition and multiplication $\bmod\ m$ iff $m$ is a prime I am looking for ways to prove that $\mathbb{Z}_m=\{0,1,2,\dots,m-1\}$ is a field under addition and multiplication $\bmod\ m$ iff $m$ is a prime.   I tried it this way: If $m$ is a prime $p$,it is obvious that most importantly, we need to prove that every non-zero element in $\mathbb{Z_p}$ has an inverse in $\mathbb{Z_p}$.We note that if $a,b\in \mathbb{Z_p}$, then $a\cdot b\in \mathbb{Z_p} \dots \boxed{*}$. Next, $a^p\equiv a \bmod p$ for prime $p$(the proof follows by induction on $a$).As  $\displaystyle 0\leq a\leq p-1$,$a\not =p$. Thus $$a^{p-1}\equiv 1 \bmod p$$ for prime $p$ which,together with $\boxed{*}$ guarantees the existence of an inverse in $\mathbb{Z_p}$.Proving the other properties is simple.  Conversely,if $\mathbb{Z_m}$ is a field,then every non-zero element of $\mathbb{Z_m}$ has an inverse.Note that inverse of an element is unique.For if $a\cdot b\equiv a\cdot c\equiv 1 \bmod m$,then $(a\cdot b)\cdot c\equiv c\equiv (a\cdot c)\cdot b\equiv b \bmod m$ i.e $m|(b-c)\implies b-c=0(0\leq a\leq m-1,a\in \mathbb{Z_m})$.So, inverses must be unique and every element is either an inverse of itself or has in inverse in the field.That allows us to conclude that $[(m-1)!]^2\equiv 1 \bmod m$ which can only mean that either  $(m-1)!\equiv 1 \bmod m$ or $(m-1)!\equiv -1 \bmod m$. If $m$ is not a prime, it has a prime factor, say $p$. $ 0\leq p\leq m-1\implies p|(m-1)!\implies p|1$or $-1$ which is absurd, a contradiction.Thus $m$ is prime.  I feel that this method is too involved and complicated. Can anyone please suggest some other method?(Some context: This is a problem from Finite Dimensional Vector Spaces by Paul Halmos. I am learning linear algebra for the first time.It seems some of the comments have been posted on the assumption that I know rings and fields; I don't. ) My background and gameobjects are 2d sprites not UI images ,I want to know how to make my background scale with screen size and positions of 2d sprits on it don't change after building game (webGl) like scale canvas with screen size and anchor points in UI elements .  Before building the game   After building I am trying to use following apex class with invocable method but its not showing in process builder.  global with sharing class SlackOpportunityPublisher {      private static final String slackURL = 'https://testsalesforceapps.slack.com/';      global class Oppty {         @InvocableVariable(label='Opportunity Name')         global String opptyName;         @InvocableVariable(label='Stage')         global String stage;     }      @InvocableMethod(label='Post to Slack')     global static void postToSlack(List&lt;Oppty&gt; oppties) {         Oppty o = oppties[0]; // If bulk, only post first to avoid overloading Slack channel         Map&lt;String,Object&gt; msg = new Map&lt;String,Object&gt;();         msg.put('text', 'The following opportunity has changed:\n' + o.opptyName + '\nNew Stage: *' + o.stage + '*');         msg.put('mrkdwn', true);         String body = JSON.serialize(msg);             System.enqueueJob(new QueueableSlackCall(slackURL, 'POST', body));     }      global class QueueableSlackCall implements System.Queueable, Database.AllowsCallouts {          private final String url;         private final String method;         private final String body;          global QueueableSlackCall(String url, String method, String body) {             this.url = url;             this.method = method;             this.body = body;         }          global void execute(System.QueueableContext ctx) {             HttpRequest req = new HttpRequest();             req.setEndpoint(url);             req.setMethod(method);             req.setBody(body);             Http http = new Http();             HttpResponse res = http.send(req);         }      }  } Can I visit the US twice within a 90 day period under the Visa Waiver Programme? 2nd time is only to transfer (change terminal, not airside). Does a non-abelian semigroup without identity exist? Change the URL in the browser without loading the new page using JavaScript How would I have a  action that may have some effects on the current page but would also change the URL in the browser so if the user hits reload or bookmark, then the new URL is used?    It would also be nice if the back button would reload the original URL.  I am trying to record JavaScript state in the URL. Finding $\lim\limits_{x\to1^-}\Bigl(\prod\limits_{n=0}^{\infty}\Bigl(\frac{1+x^{n+1}}{1+x^n}\Bigr)^{x^n}\Bigr)$ Compute : $$L=\lim_{x\to 1^-} \left(\prod_{n=0}^{\infty} \left(\frac {1+x^{n+1}}{1+x^n}\right)^{x^n}\right)$$   My try:   Writing out the first few terms I noticed that the limit can be expressed as $$L=\lim_{x\to 1^-} \frac 12\left(\prod_{n=1}^{\infty} (1+x^n)^{x^{n-1} -x^n}\right)$$ $$L=\frac 12\lim_{x\to 1^-} \left(\prod_{n=1}^{\infty} (1+x^n)^{x^{n-1}}\right)^{1-x}$$  Converting to exponential form I get $$L=\frac 12 \exp {\left(\lim_{x\to 1^-} (1-x)\sum_{n=1}^{\infty} \left(x^{n-1}\ln(1+x^n)\right)\right)}$$  And got stuck here. I did try to use approximation $\ln x\sim x$ hereon to get final answer as $\frac {\sqrt e}{2}$ but I think it was improper to use approximation and hence I believe that the answer I got is flawed. I also noticed that the form I obtained is quite similar to be used for a Riemann Sum but I didn't get a way to tackle the problem using that way.  Can someone please help me with this problem.... Is "tri-quarterly" a real English word meaning 3 times a year? Are there any other words that mean 3 times a year?