I think it is about time I learn the difference.  I have seen how to use these, but the tutorials have been kinda vague.  I have a very basic knowledge on the syntax and how to use them to a very small extent.  Pointers have always seemed kinda scary and confusing.  I have heard once you learn to use them they are great, and I want something great :).  So how can I use these and at what time should I use each one?  One more thing, I am using C++.  Thank you!
I know references are syntactic sugar, so code is easier to read and write. But what is the difference between a pointer variable and a reference variable?
If verification is quality control, what is a validation? Statistics and causal inference? How to pass argument to script which is input to bash It's become clear that last night's (Tues Jan 8th 2019) patches to Windows 7 broke SMB2 networking in Lanman Server.  One or both of KB 4480970 and KB 4480960 results in any OS that uses SMB2 (such as Windows XP, some Windows 7, and same generation server OS' and Mac OS X machines (certainly 10.10, 10.11 not sure about others yet)) being unable to connect to Windows 7 Pro shares.  Client machines repeatedly prompt for login despite credentials being correct. problem with surfaces on tkz-fct i am using this wonderful tool that tkz-fct is for creating nice documents but I have a weird result from recently. This is my document :  \documentclass[10pt,a4paper]{article} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{calc} \usepackage{color} \usepackage{pifont}                     %pour utiliser la police Ding \usepackage[left=1.5cm,right=1.5cm,top=2cm,bottom=2cm]{geometry} %marges du document \usepackage[french]{babel} \usepackage[usenames,dvipsnames]{xcolor} \usepackage[L]{thmbox} \usepackage{eurosym} \usepackage{enumitem}               %pour modifer itemize et enumerate \usepackage{amsmath,amsfonts,amssymb} \usepackage{mathrsfs}               %pour utiliser mathscr \usepackage{array,multirow,makecell} \usepackage{fancyhdr}               %package pour modifier les en-têtes \usepackage{fancybox}               %pour boîtes spéciales \usepackage{tikz,tkz-tab,tkz-fct} \usepackage{tikz-dependency}        %permet de créer des schemas \usepackage{sectsty}                %permet de modifier les styles des sections (voir \sectionfont l.21) \usepackage{fourier-orns} \usepackage{shadethm}               %pour theoremes en gris \setcellgapes{1pt} \makegapedcells \newcolumntype{R}[1]{&gt;{\raggedleft\arraybackslash }b{#1}}   %pour redéfinir les colonnes dans tabular \newcolumntype{L}[1]{&gt;{\raggedright\arraybackslash }b{#1}} \newcolumntype{C}[1]{&gt;{\centering\arraybackslash }b{#1}} \renewcommand{\thesection}{\Roman{section}} %permet de changer la numérotation en chiffres romains des sections \newshadetheorem{defi}{Définition}  %crée un nouveau type de théorème \newshadetheorem{thm}{Théorème} \newshadetheorem{ppte}{Propriété} \sectionfont{\sectionrule{3ex}{3pt}{-1.5ex}{1pt}} %mettre un trait de séparation dans les sections (package sectsty) \pagestyle{fancy} %style en-têtes \lhead{} %en-tête gauche \chead{Lois à densité} %en-tête centrale \rhead{T\up{ale}} %en-tête droite \begin{document} \begin{tikzpicture}      \tkzInit[xmin=-4,xmax=4,ymax=1]      \tkzDrawX[label={},noticks]      %\tkzDrawY      \tkzFct[domain=-2:2]{exp(-x**2)}      \tkzDrawArea[color=blue, domain = -0.5:1]      \tkzText(-1,0.75){$\mathscr{C}_{f}$} \end{tikzpicture} \end{document}   But from now, it doesn't produce the result I would like as the surface start from the point (-0.5,f(-0.5)) and not as an integral from -0.5 to 1. This is a picture of the result :   Which is obviously not what I would like and this extends now to all my "old" docs which were "normal" before. I don't think I have done anything special except updating my Tex distribution ... If someone has an idea ?? Beamer item balls go missing while compiling in XeLateX since yesterday's TeXlive update, however, the same code works with pdfLaTeX. Any solution, please. Here is my MWE: \documentclass{beamer}  \setbeamertemplate{itemize item}[ball] \setbeamertemplate{enumerate item}[ball]  \begin{document}  \begin{frame} \frametitle{A tested title} text \begin{enumerate}     \item this is an item \end{enumerate} text3 \begin{itemize}     \item this is an item \end{itemize} \end{frame} \end{document} Using VHDL code to design a JK Flip Flop I'm using quartus II to design a JK Flip Flop. However, my results show unknown output. Why is it?  Intended design circuit:    VHDL code:  library IEEE;  use IEEE.STD_LOGIC_1164.ALL;  entity JKFlipFlopGate is     port(         J,K,Clk : in std_logic;             --JK Flip-Flop gate input 1 &amp; 2         Q,Qbar : out std_logic              --JK Flip-Flop gate output     ); end JKFlipFlopGate;  architecture result of JKFlipFlopGate is         signal out1,out2,out3,out4 : std_logic;  begin     out1    &lt;= NOT(J AND Clk AND out4);                      out2    &lt;= NOT(K AND Clk AND out3);      out3    &lt;= out1 NAND out4;     out4    &lt;= out2 NAND out3;      Q       &lt;= out3;     Qbar    &lt;= out4;     end result; Should my first trip be to the country which issued my Schengen Visa? Why do birds sitting on electric wires not get shocked? How can I donate to Ubuntu without PayPal? When I wanted to download Ubuntu 12.10 from ubuntu.com, I was asked to make a donation. However, there is only a PayPal option to make the payment. But I don't use PayPal. Is there any other option to make the payment? I updated some entries in the  at C:\WINDOWS\System32\drivers\etc.  As a test, I decided to make Google point to 127.0.0.1.  # Additionally, comments (such as these) may be inserted on individual # lines or following the machine name denoted by a '#' symbol. # # For example: # #      102.54.94.97     rhino.acme.com          # source server #       38.25.63.10     x.acme.com              # x client host  127.0.0.1       localhost ::1             localhost 127.0.0.1       google.com   This works fine on Windows Vista, but not on Widows 7. When I type google.com into my browser, it goes directly to Google's website.  I am not using a proxy server, and I think there might be some temporary DNS settings that need to be flushed, but I'm not sure.  Does anyone know how to fix this? How can I solve this functional equation, where $x,y$ are any real numbers and $f:\mathbb{R}\to \mathbb R$ is a function such that : $$f(x+y)+f(x-y)=2f(x)\cos y$$    I tried substituting $x=0$ to get $f(y)+f(-y)=2f(0)\cos y$ . Taking $x=y$ gives $f(2x)+f(0)=2f(x)\cos x$. I similar get some more relations like that, but its not really helping me in finding anything useful. I also think the function must either be $\sin$ or $\cos$ looking at the product to sum formulae. Can anyone tell me how should I solve this? Exec format error of gcc-compiled Hello World c++ On AWS Ubuntu Server, I wrote C++ Hello, World program:  #include &lt;iostream&gt; using namespace std;  int main(){         cout&lt;&lt;"Hello, World!"&lt;&lt;endl;         return 0; }   And compiled it:  ubuntu@ip-xxxxx:~/dev/c++$ g++ -c ./test.cc -o out ubuntu@ip-xxxxx:~/dev/c++$ chmod a+x out ubuntu@ip-xxxxx:~/dev/c++$ ./out -bash: ./out: cannot execute binary file: Exec format error ubuntu@ip-xxxxx:~/dev/c++$ file ./out ./out: ELF 64-bit LSB  relocatable, x86-64, version 1 (SYSV), not stripped ubuntu@ip-xxxxx:~/dev/c++$ uname -a Linux ip-xxxxx 3.13.0-48-generic #80-Ubuntu SMP Thu Mar 12 11:16:15 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux ubuntu@ip-xxxxx:~/dev/c++$ gcc --version gcc (Ubuntu 4.8.4-2ubuntu1~14.04) 4.8.4   It seems that architecture x86-64 is the same each other. What is the problem here? Do I have to add more C++ flags? My PC was working yesterday without any problem. I shut it down and tried to open this morning. It prints out these messages on the black screen:  systemd-udevd[713]: failed to execute '/bin/systemctl' '/bin/systemctl start --no-block nvidia-persistenced.service': No such file or directory  systemd-udevd[852]: failed to execute '/bin/systemctl' '/bin/systemctl stop--no-block nvidia-persistenced': No such file or directory   It then continued with the login screen. I entered my password and pressed enter. It waited for a while and the login screen reappeared again.  How can I fix the problem? What does bookmarking a question mean? How do you bookmark a question? Do users get updates on their bookmarked questions? Are my bookmarks publicly visible? How do you see your own bookmarks? How do you see other users' bookmarks? How do you see which users have bookmarked a particular question? What impact does the bookmark system have on the voting system? Can I &quot;un-bookmark&quot; a question? Can I search within my bookmarks? I've seen many boads with weird zig-zag shaped tracks just like the one below. Why are they designed like that? Can't operator == be applied to generic types in C#? According to the documentation of the == operator in ,      For predefined value types, the   equality operator (==) returns true if   the values of its operands are equal,   false otherwise. For reference types   other than string, == returns true if   its two operands refer to the same   object. For the string type, ==   compares the values of the strings.   User-defined value types can overload   the == operator (see operator). So can   user-defined reference types, although   by default == behaves as described   above for both predefined and   user-defined reference types.   So why does this code snippet fail to compile?  bool Compare&lt;T&gt;(T x, T y) { return x == y; }   I get the error Operator '==' cannot be applied to operands of type 'T' and 'T'. I wonder why, since as far as I understand the == operator is predefined for all types?  Edit: Thanks, everybody. I didn't notice at first that the statement was about reference types only. I also thought that bit-by-bit comparison is provided for all value types, which I now know is not correct.  But, in case I'm using a reference type, would the == operator use the predefined reference comparison, or would it use the overloaded version of the operator if a type defined one?  Edit 2: Through trial and error, we learned that the == operator will use the predefined reference comparison when using an unrestricted generic type. Actually, the compiler will use the best method it can find for the restricted type argument, but will look no further. For example, the code below will always print true, even when Test.test&lt;B&gt;(new B(), new B()) is called:  class A { public static bool operator==(A x, A y) { return true; } } class B : A { public static bool operator==(B x, B y) { return false; } } class Test { void test&lt;T&gt;(T a, T b) where T : A { Console.WriteLine(a == b); } } Encrypt home drive after installation I declined to encrypt to my home drive whilst installing ubuntu.  Is it possible to encrypt it after installation?  if so, how? Variable substitution with an exclamation mark in bash It appears that in anticipation of D&amp;D Next Wizards of the Coast has removed much of the Dungeons and Dragons, 3rd Edition Web content. I didn't perform a thorough search to determine if all the content is removed (e.g. I know the Three Dragon Ante Web enhancement  and the Mind's Eye column about psionic tattoos  are both gone--better not to ask why those are my go-to articles), but it all might be.  What's the best way--and by best I mean both legal and convenient--to continue to access this content?