struct node{       struct node next;       int id;   }   gives "field next has incomplete type error ".    what is wrong with this struct ?
I haven't been writing C for very long, and so I'm not sure about how I should go about doing these sorts of recursive things... I would like each cell to contain another cell, but I get an error along the lines of "field 'child' has incomplete type". What's up?  typedef struct Cell {   int isParent;   Cell child; } Cell;
I'm having some troubles understanding the solution (going from step $2$ to step $3$) of this linear congruence equation. Here's the problem with the solution:   Solve the congruence $2x + 11 \equiv 7 \pmod 3$.   First, we reduce all the coefficients $\pmod 3$:  $$2x + 2 \equiv 1 \pmod 3. \tag{1}$$  Next, we add $1$ to both sides, using the fact that $2 + 1 \equiv 0 \pmod 3$:  $$2x \equiv 2 \pmod 3. \tag{2}$$  Finally, we multiply both sides by $2$, using the fact that $2 · 2 = 4 \equiv 1 \pmod 3$:  $$x \equiv 1 \pmod 3. \tag{3}$$  That is, any number in the set $\{\ldots, −5, −2, 1, 4, \ldots\}$ will solve the original congruence.    Like I said my problem is the step between $(2)$ and $(3)$. If I multiply both sides of $(2)$ by $2$ I get:  $$4x \equiv 4 \pmod 3.$$  Now, I understand that $4$ is congruent to $1 \pmod 3$ so the RHS "simplifies" to $1 \pmod 3$ but I don't understand why the LHS "simplifies" to $x$. Can someone help me with this? Convert Month Number to Month Name Function in SQL I have months stored in SQL Server as 1,2,3,4,...12. I would like to display them as January,February etc. Is there a function in SQL Server like MonthName(1) = January? I am trying to avoid a CASE statement, if possible. With Glade Designer that lets you set up Gtk-Ui's you can check the option that windows are not shown in the launcher. If I take a look at the ui-file generated by Glade, it says &lt;property name="skip_taskbar_hint"&gt;True&lt;/property&gt;. In gtk code this hint is  window.set_property('skip-taskbar-hint', True). However I believe that this option is not exclusively Gtk-specific, and want to apply this one on my PyQt4-app. The Ubuntu window manager must be able to receive that hint, otherwise I would see the window of a gtk-application i use (stickynotes-indicator). So there MUST be a way of doing this in Qt or any other language, right?  Does anybody know such an option? Python or Qt syntax, doesn't matter! How to determine if .NET code is running in an ASP.NET process? I have an instance of a general purpose class that will be executed both under ASP.NET and a stand alone program. This code is sensative to the process where it is being run - that is, there are certin methods that should not called if running under ASP.NET. How do you determine if the code is executing in an ASP.NET process?  The solution I am currently using is answered below.    I wish someone would add a comment as to why this question has gotten downvoted and/or propose a better way to ask it! I can only assume at least some folks have looked at the question and said "what an idiot, ASP.NET code is .NET code". Can I visit other Schengen countries on a long-term Schengen visa or residency permit? How to pause with specific time between two command in script? I want to do such as following:  #!/bin/bash command1 pause 30 seconds command2 exit   This is only example script with pause of 30 seconds between run of 2 command.  How to do this? My computer no longer boots Windows or the installed operating system. Instead, I may get this error:  PXE-E61: Media test failure, check cable -or- Check cable connection!  PXE-M0F: Exiting PXE ROM.   and/or one of the following messages or similar:  Operating System not found  No boot device available- No bootable devices--strike F1 to retry boot, F2 for setup utility  No bootable device -- insert boot disk and press any key  No Boot Device Found. Press any key to reboot the machine  Default Boot Device Missing or Boot Failed  Reboot and Select proper Boot device or Insert Boot Media in selected Boot device   What does this mean and what can I do?     This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details. Are there other explanations for slow tyre pressure loss? I rode my road bike on Friday and the tyres were at the correct pressure then, around 100psi.  On Tuesday, I jumped on without checking them and quickly realised something was wrong with the rear tyre.  It wasn't completely flat but was fairly soft.  I hadn't gone far so went home and took the car to work instead.  When I got home later, I was surprised to find the tyre, while still soft, hadn't lost all pressure by any means.  It was around 40psi and felt the same as when I left it in the morning.  I decided there must be a slow leak somewhere, but I couldn't find one anywhere, putting the inner under water and going around it methodically looking for bubbles.  I've never failed to find a leak before that way.  I've switched it out anyway because I don't want to mess around with my commute, but I'm curious ... is there another explanation for that amount of pressure loss?  Or must there have been a puncture somewhere that I missed somehow?  The tyres (whole bike) are pretty new and in excellent condition. Function return object Continuously copy all file changes from one folder to another on change (Windows) I'm working on a massive Java web application which is kept under centralized version control, but the source files are used to build and run the actual server, which then copies all the files I work on into a random temporary directory while it's running.  My problem is that I need to either rebuild this huge application to see any changes to my files, or keep track of all my changes and copy over the files I've changed back to their source location before committing them back to source control.  My question is: is there a command line script I can run that will monitor any changes in the source folder and automatically copy changed files across to temporary folder X?  The idea is to remove the human point of failure in having to manually mitigate the two-locations problem. I would like to use client-side Javascript to perform a DNS lookup (hostname to IP address) as seen from the client's computer. Is that possible? General way to determine $\mathbb{Q}(\gamma) = \mathbb{Q}(\alpha,\beta)$ given $\alpha$ and $\beta$ Calculating percentage of overlap between 2 features from 2 different layers using ArcGIS Desktop? I have two layers. Layer 1 has features that are property/parcels with area in acres. Layer 2 has features that are wetlands/bodies of water with area in acres. I want to calculate parcels that have for example 0% wetlands, 10% wetlands, 20% wetlands, 30% wetlands etc. to 100% wetlands.   How can I do this on ArcGIS Desktop?   Ideally, I want to find parcels/properties that have a limited number or a limited percentage of wetland coverage. Ubuntu/Kubuntu 16.04.1 installation in VirtualBox I'm trying to install Kubuntu 16.04.1 on a virtual machine (I'm using VirtualBox). When I boot from the disk image Ubuntu begins to load and then I get this screen:   It looks like it's loading but the display is not working properly (the pink blob is my mouse pointer, only very large and pink).  I also tried installing Ubuntu 16.04.1 and I get a very similar result:   Am I missing something in VirtualBox? Thanks! What could cause a microcontroller to unexpectedly reset? One particularly irritating variety of bug in a microprocessor-controlled system is for the microprocessor to unexpectedly reset. An important tool for debugging this kind of problem is a list of possible causes. What could cause a microcontroller to unexpectedly reset? I have a text file abc.txt and its contents are:     /lag/cnn/org/one.txt    /lag/cnn/org/two.txt    /lag/cnn/org/three.txt   If I use:  $ tar -cvf allfiles.tar -T abc.txt   I'm getting the tar of files in the list. Similarly is it possible to copy those files in abc.txt to a folder?  I tried this:              $ cp --files-from test1.txt ./Folder   But it is not working. Perhaps this is trivial: how does one prove that the work done by a homogeneous gravitational field on a system of particles is equal to the work done on a point mass with the total mass of the system, located at the center of mass of the system. fontenc vs inputenc How can a computer with dynamic IP work as a webserver? How can a computer with dynamic IP work as a WebServer? In the movie Harry Potter and the Goblet of Fire, there's a scene where the students are preparing for the Yule Ball.   Professor McGonagall is instructing the boys and girls, while Filch is choosing a vinyl record to place in an enormous turntable phonograph with a horn as big as Hagrid.   This has me wondering if the wizarding world, in general, plays vinyl records. Or, if this was just a Muggle artifact that Hogwarts kept as a novelty.   Are there other instances of witches or wizards using or owning phonographs or record players in either the books or movies? If so, what are they? (Examples help to illustrate if this was a one-off or a trend)