When I use two variables in a for loop with different conditions two conditions like I have used below i&lt;3,j&lt;2 the for loop is always executing till the second condition fails.  #include&lt;iostream&gt; #include&lt;conio.h&gt; using namespace std ; int main() { int i,j ; for(i=0,j=0;i&lt;3,j&lt;2;i++,j++) {     cout&lt;&lt;"hello" ; } getch() ; return 0 ; }    In that code, hello is printed 2 times. Why?  If I use i&lt;3,j&lt;10, "Hello" is printed 10 times. I can't understand why the first condition is being neglected. Is it compiler dependent or something else?  Every thing works normal if I replace with conditions like || (OR) or &amp;&amp;(AND).An other thing is that I cannot initialize i and j in the for loop itself, it is showing me an error, but works fine when I declare variables in C style or one variable outside the for loop, why is it so?  Compiler I have used is Orwell Dev C++. Thanks in advance.
How does the comma operator work in C++?  For instance, if I do:  a = b, c;     Does a end up equaling b or c?   (Yes, I know this is easy to test - just documenting on here for someone to find the answer quickly.)  Update:  This question has exposed a nuance when using the comma operator.  Just to document this:  a = b, c;    // a is set to the value of b!  a = (b, c);  // a is set to the value of c!   This question was actually inspired by a typo in code.  What was intended to be  a = b; c = d;   Turned into  a = b,    //  &lt;-  Note comma typo! c = d;
Is it possible to access a 64-bit dll from a 32-bit application? $ ls -l /tmp/test/my\ dir/ total 0   I was wondering why the following ways to run the above command fail or succeed?  $ abc='ls -l "/tmp/test/my dir"'  $ $abc ls: cannot access '"/tmp/test/my': No such file or directory ls: cannot access 'dir"': No such file or directory  $ "$abc" bash: ls -l "/tmp/test/my dir": No such file or directory  $ bash -c $abc 'my dir'  $ bash -c "$abc" total 0  $ eval $abc total 0  $ eval "$abc" total 0 Good keyboard layouts for typing (La)TeX When typing (La)TeX some keys are used a lot more often then in plain text, especially \, {, }, [, ], $, ^ and _. On most keyboard layouts these keys are rather cumbersome to type. The English QWERTY keyboard is a lot better than the German QWERTZ, but is still far from optimal.  Given that I mostly type mathematical texts in English, what keyboard layout would you recommend?  Bonus points for the following:   Ability to type non-English Latin characters, especially German umlauts. Some similarity to QWERTZ or QWERTY as I'm most used to these layouts (I currently use the US-International layout from Linux) Ability to type math symbols directly (Greek letters, \times, etc.) Understanding the proof for $\gcd (F_n, F_{n+k}) = 1$ where $F_n$ is a Fermat number I'm trying to understand the following proof of why      No two Fermat numbers have a common divisor greater than $1$.   Hardy and Wright show the following proofs:   If $x = 2^{2^n}$, we have  $$\frac{F_{n+k} - 2}{F_n}(\circ) = \frac{2^{2^{n+k}}-1}{2^{2^n}+1} = \frac{x^{2^k}-1}{x+1} = x^{2^k-1} - x^{2^k-2} + \ldots -1$$  The main issue I'm having is the $\circ$ part. I don't understand how they get that. The rest of the proof makes sense but the first part is really confusing me. Can someone please explain where they get that fraction?  Thanks a bunch! Alternating sum of binomial coefficients: given $n \in \mathbb N$, prove $\sum^n_{k=0}(-1)^k {n \choose k} = 0$ Let $n$ be a positive integer. Prove that   \begin{align} \sum_{k=0}^n \left(-1\right)^k \binom{n}{k} = 0 . \end{align}   I tried to solve it using induction, but that got me nowhere. I think the easiest way to prove it is to think of a finite set of $n$ elements, but I can't find the solution. Colorizing your terminal and shell environment? I spend most of my time working in Unix environments and using terminal emulators. I try to use color on the command line, because color makes the output more useful and intuitive.  What options exist to add color to my terminal environment? What tricks do you use? What pitfalls have you encountered?  Unfortunately, support for color varies depending on terminal type, OS, TERM setting, utility, buggy implementations, etc.  Here are some tips from my setup, after a lot of experimentation:   I tend to set TERM=xterm-color, which is supported on most hosts (but not all). I work on a number of different hosts, different OS versions, etc. I use everything from macOS X, Ubuntu Linux, RHEL/CentOS/Scientific Linux and FreeBSD. I'm trying to keep things simple and generic, if possible. I do a bunch of work using GNU screen, which adds another layer of fun. Many OSs set things like dircolors and by default, and I don't want to modify this on a hundred different hosts. So I try to stick with the defaults. Instead, I tweak my terminal's color configuration. Use color for some  (ls, grep, less, vim) and the . These commands seem to use the standard "". For example:  alias less='less --RAW-CONTROL-CHARS' export LS_OPTS='--color=auto' alias ls='ls ${LS_OPTS}'    I'll post my .bashrc and answer my own question Jeopardy Style. Determine the Galois group of $\mathbb{Q}(\sqrt{a+b\sqrt{d}})$ I have this file:  sometext1{ string1 }  sometext2{ string2 string3 }  sometext3{ string4 string5 string6 }   I want to search this file for a specific string and print everything before this string up to the opening { and everything after this string up to the closing }. I tried to achieve this with sed but if I try to print everything in the range /{/,/string2/ for example sed prints this:  sometext1{ string1 }  sometext2{ string2 sometext3{ string4 string5 string6 }   If I search for the string "string2" I need the output to be:   sometext2{ string2 string3 }   Thanks. pgfplots - barplot with multiple bars on same coordinate, but labelled differently I'm showing several data sets next to each other using multiple \addplot commands within a pgfplots axis environment. These are then further grouped into categories. The output of the graph per se is fine, however, I need each bar to be labelled separately - basically, I want the legend to be displayed directly underneath its corresponding element. I presume a picture will illustrate my problem more clearly:     I prepared an MWE:  \documentclass{minimal} \usepackage{pgfplots}  \begin{document}  \pgfplotstableread{ 0 35569 8842    134984   1 30428 4689    34077 2 32920 6207    73787    3 16462 7562    23496    4 12315 8572    16565    5 76572 19572   26030    }\dataset \begin{tikzpicture} \begin{axis}[ybar,         width=.9\textwidth,         ymin=0,         ymax=150000,                 ylabel={Y-Label},         xtick=data,         xticklabels = {             Category 1,             Category 2,             Category 3,             Category 4,             Category 5,             Category 6         },         major x tick style = {opacity=0},         minor x tick num = 1,         minor tick length=2ex,         ] \addplot[draw=black,fill=black!20] table[x index=0,y index=1] \dataset; %Data1 \addplot[draw=black,fill=black!40] table[x index=0,y index=2] \dataset; %Data2 \addplot[draw=black,fill=black!60] table[x index=0,y index=3] \dataset; %Data3 \legend{Data1,Data2,Data3} \end{axis}  \end{tikzpicture}  \end{document} ESTA approved on the same day as B-1/B-2 visa refused I am writing because I have a question regarding my ESTA application and because I could not find a similar case online that would help me at this stage. I have never been to the U.S. so this would be my first visit.    I am a German citizen, hence eligible for the Waiver Program. I applied for an ESTA in June 2014 and got approved. After further research on the Internet I learned that the passport should be valid until 6 months after the planned return date. My passport was due to run out in Feb 2015 - which still should have been fine but because I didn't want to take chances I applied for a new passport which was issued August 2014 and is now valid until August 2024. My passport number has been changed also.    After I received my new passport I was advised by a friend to apply for a B-1/B-2 visa as it would allow me to extend my stay and it seemed like a good idea at first. On the day of my interview I also applied for a new ESTA with my new passport number (just in case) which again was granted.   Unfortunately for me the interview for the B-1/B-2 visa was unsuccessful and I got rejected. I was not aware then that after a rejected interview one could not travel with ESTA, otherwise I would have never risked it!  Now I am very concerned, can I still use my ESTA and enter the U.S.? as I read everywhere that once you get rejected the chances of getting through are very slim and any visa rejection will result in not being able to use the waiver program.  It might be important to note that both the B-1/B-2 interview and the waiver application were on the same day, 21st of August 2014, so depending on how one might look at it that might present a problem too I suppose.  I guess the frustration lies in the fact that I did not need to apply for a B-1/B-2 visa to begin with, and had I not I would now not have these problems. I would like to know how likely it is that I can still travel under the waiver program, if at all, and what my options are at this point. In my opinion the accepted answer should permanently stick as only the original question submitter has the ability to accept. Where and why do I have to put the "template" and "typename" keywords? Why is "night" spelled with "gh"? As far as I know, humans have 23 pairs of chromosomes, each one which contains a particular amount of genes. But in the "last" pair, men have a XY pair chromosome, and women have a XX pair chromosome. Does the missing "leg" of the XY pair make men to have fewer genes than women, and if so, how many genes do each sex have? Merge around a face So, I'm working on a control station that has buttons. It is a one-mesh creation, that means, I don't want to create buttons and things like that separated from the main mesh, but as you can see, I have problems. I would like to make the highlighted parts to be one with the main part around them. I've tried everything, and I have this problem on multiple creations. Any idea?  Update: I've added another example of the problem. I want them to be one face, instead of two. (2nd picture) I have two raster files that are the same cell size but I cannot get them to align properly. (I want the black to line up with the pink)    When creating the black raster file (from using polyline to raster), I imported the pink raster in the Snap Raster section in the Environments setting. I thought that Snap Raster was supposed to make it line up?  Am I doing something wrong or is it a bug in Arc (I remember reading that this was a problem about two years ago), and if it is a bug is there a work around?  I have also read there is a Raster Shift, but I'm not sure what to enter in the X Coordinate and Y Coordinate. Since I only want the black raster to shift down, I know that the X Coor = 0 and the Y Coor should be negative something, but what are the units?  Thanks. I have run into a conundrum.   When I go to get some friends cans of beer I say:     You guys want a beer?   When I am referring to going to a bar and drinking some I say:     Let's go get some beers!   When I go to a store to buy beer I say:     I am going to get beer.   How can I work this out? My friend is a native Chinese speaker and this is the sort of plural thing that trips her up. How is this explained? Indefinite integral of secant cubed I need to calculate the following indefinite integral:  $$I=\int \frac{1}{\cos^3(x)}dx$$  I know what the result is (from Mathematica):  $$I=\tanh^{-1}(\tan(x/2))+(1/2)\sec(x)\tan(x)$$  but I don't know how to integrate it myself. I have been trying some substitutions to no avail.   Equivalently, I need to know how to compute:  $$I=\int \sqrt{1+z^2}dz$$  which follows after making the change of variables $z=\tan x$. How to count entities with commands/check if there are only one or a certain number of entities or players left? I want to run a command when there are only 10 entities left. I know you can use /execute unless entity to detect when all matching mobs have died, but it doesn't work if you want to run a command when there are for example 10 entities left.  A command like /execute if entity @e[limit=10] does not work, it also triggers if there is only one entity.  Such a counting system could also be used to determine once there is only one player left in an arena, meaning they have won a battle or similar. If $\sin \theta+\cos\theta+\tan\theta+\cot\theta+\sec\theta+\csc\theta=7$, then $\sin 2\theta$ is a root of $x^2 -44x +36=0$ My own bonafide attempt. $$ 0&lt;\theta&lt;\pi/2$$   and $$\sin\theta+\cos\theta+\tan\theta+\cot\theta+\sec\theta+\csc\theta=7$$   then show that $\sin 2\theta$ is a root of the equation $$x^2 -44x +36=0$$   I tried to use the above given equation of all the trigonometric ratios, though I ended up with an expression of $\sin\theta\cos\theta$.   But this too is in the form of $\sin\theta$ and $\cos\theta$ which was $\sin\theta\cos\theta=\frac{1}{6-\sin\theta-\cos\theta}$.  When I put that in the quadratic equation, it would again transform into the form of $\sin\theta$ and $\cos\theta$, and hence at last I couldn't prove the thing.  Even hints would work, as I would like to solve the question myself.