I wonder if anyone can explain how the System.double is different from System.Double and how these differences are constructed in code.  if one looks at the Class:  public struct Double : IComparable, IFormattable, IConvertible, IComparable&lt;Double&gt;, IEquatable&lt;Double&gt;   from:   There is no clarity between the double and Double Types.  Using Visual Studio 2015, it is recommended that one uses the double key word instead of Double as the conversion is less.  If I were to write a custom Data Type and derive from double, for example, would constructing it by dynamic be enough to get the ball rolling.  It baffles me at how .NET has derived the base Data Types.  EDIT: A search on the net shows there is a lot of confusion on this topic. For example:  using System;  public class QBit : IComparable, IFormattable, IConvertible {  internal _qbit  public string Value { get { return _qbit; }  public QBit() { _qbit = "1978"; }  }   In another class:  using System;  using qbit = QBit;  public class Spinstate {  internal _state  public string Value { get { return _state; }  public QBit() { qbit = new QBit (); _state = qbit.Value; }  }   Is not the same as a , this is an . How to declare a Keyword?  EDIT: A KEYWORD is defined as:     Keywords are predefined reserved identifiers that have special meanings to the compiler. They cannot be used as identifiers in your program unless they include @ as a prefix. For example, @if is a legal identifier but if is not because it is a keyword.   The  '' is defined as follows:     The double keyword signifies a simple type that stores 64-bit floating-point values. The following table shows the precision and approximate range for the double type.   The Type is as specified by the , which is a binary64 Double precision floating-point format - Still, we are no closer to Defining a Keyword in Code and more importantly "and how they are constructed"
Example (note the case):  string s = "Hello world!"; String s = "Hello world!";   What are the guidelines for the use of each? And what are the differences?
Is it possible to redirect a command's output to cd? For example, I searched for a directory using locate and got the path to it. Now, instead of writing a cd path, can I redirect the locate output to cd?  I tried this:  $ locate Descargas | grep Descargas$ /home/oliver/Descargas $ locate Descargas | grep Descargas$ | cd $ locate Descargas | grep Descargas$ &gt; cd $ locate Descargas | grep Descargas$ &lt; cd /home/oliver/Descargas $    No luck. This probably isn't particularly useful, but I'm curious. Why does the Community user have votes cast? If Community is a background process and not a real person then why does its profile show that it has votes cast, and how does it cast them?  How can it decide which answers to upvote or downvote?  See the massive number of upvotes and downvotes cast in its profile: How do I programmatically create a new content type? What exactly is an environment variable? I know that VARIABLE=value creates an environment variable, and export VARIABLE=value makes it available to processes created by the current shell. env shows the current environment variables, but where do they live? What comprises an environment variable (or an environment, for that matter)? software updater failed to download repository information When I run software updater it says that it failed to download repository information and to check Internet connectivity.  I have Internet connectivity.  How do I fix this?  editing to add content of sources,list:  sorry I can't figure out how to paste in the content of sources.list without making a huge mess.  Some of it previews as really large bold print.  I tried to follow the block quoting and code rules but it is a huge mess anyway. I get it after updating in Synaptic Manager  I recently did a clean install of Ubuntu 17.04 from 16.10.  error message:-  W: Download is performed unsandboxed as root as file '/var/cache/apt/archives/partial/samba-libs_2%3a4.5.8+dfsg-0ubuntu0.17.04.1_i386.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied) I want to write an application that detects when a page is loaded in the browser, then I should be able to insert content on top of the loaded web page? Anybody with an idea on how to do that?  Please note that I should be able to do this in any browser (Firefox/IE).  What language should I use to help me do this?  How do I detect this from an external application?  How should I integrate this with the browser? What are the differences between struct and class in C++? This question was .  Now I'd like to learn the differences between a struct and a class in C++. Please discuss the technical differences as well as reasons for choosing one or the other in OO design.  I'll start with an obvious difference:   If you don't specify public: or private:, members of a struct are public by default; members of a class are private by default.   I'm sure there are other differences to be found in the obscure corners of the C++ specification. Fitting linear model / ANOVA by group How do I set up an account with multiple users? As writing matrices in LaTeX is an extremely time-consuming activity, I was wondering if a software or a site exists that automatically gave the transposed form of a matrix, that is to say, given a matrix:  \begin{bmatrix}    0 &amp; -1 &amp; -1 \\    -1 &amp; -1 &amp; 0 \\    -1 &amp; 0 &amp; 1 \\    1 &amp; 0 &amp; 0 \\    0 &amp; 0 &amp; -1 \\    -1 &amp; 2 &amp; 1  \end{bmatrix}   it will produce a transposed matrix, with the columns in place of the lines and conversely...  It would be particularly time-saving! Javascript close alert box I want to be able to close an alert box automatically using Javascript after a certain amount of time or on a specific event (i.e. onkeypress).  From my research, it doesn't look like that's possible with the built-in alert() function.  Is there a way to override it and have control over the dialog box that it opens?  Also, I don't want an override that shows a hidden div as the alert.  I need an actual dialog box. Does equality of characteristic polynomials guarantee equivalence of matrices? I have a qualifying exam coming up in a couple days and I am just trying to understand some pathological examples I have in my notes. I will list a similar problem which I know the solution to and then the question.  True or False:   let $A,B \in \mathbb{Q}^{n \times n }$  Suppose $xI-A$ and $xI-B$ are equivalent then $\det(xI-A) = \det(xI-B)$.     I wrote in my notes this is true because any two matrices are equivalent in $\mathbb{Q[x]}^{n \times n}$ if and only if they have the same invariant factors.  Since the characteristic polynomial is a product of the invariant factors it follows that $\det(xI-A) = \det(xI-B)$.        True or False:   let $A,B \in \mathbb{Q}^{n \times n }$. If $\det(xI-A) = \det(xI-B)$ (in $\mathbb{Q}[x]$) then $xI-A$ and $xI-B$ are equivalent  in $\mathbb{Q}[x]^{n \times n}$   I think this is false because of the fact that equality of determinants is not strong enough to guarantee all invariant factors are equal but I do not have an example. How do I get:  id       Name       Value 1          A          4 1          B          8 2          C          9   to  id          Column 1          A:4, B:8 2          C:9 Normal text is invisible when using beamer with notes and XeLaTeX sed command not giving proper output for regular expression used I am trying to fetch data between a range of time intervals from the log file. However, the complete data is not fetched for the end date.  Below is the command used:   sed -n '/26/Nov/2018/,/30/Nov/2018/ p' /path/file.log    The data I am having in the above log file is somewhat like:   192.168.0.123 - - [25/Nov/2018:13:24:59 +0530] "Data 1"  192.168.0.123 - - [26/Nov/2018:13:24:59 +0530] "Data 2"  192.168.0.123 - - [26/Nov/2018:13:25:09 +0530] "Data 3"  192.168.0.123 - - [27/Nov/2018:13:25:09 +0530] "Data 4"  192.168.0.123 - - [27/Nov/2018:13:25:11 +0530] "Data 5"  192.168.0.123 - - [27/Nov/2018:13:25:53 +0530] "Data 6"  192.168.0.123 - - [28/Nov/2018:13:25:53 +0530] "Data 7"  192.168.0.123 - - [29/Nov/2018:13:25:53 +0530] "Data 8"  192.168.0.123 - - [30/Nov/2018:13:25:53 +0530] "Data 9"  192.168.0.123 - - [30/Nov/2018:13:25:53 +0530] "Data 10"  192.168.0.123 - - [01/Dec/2018:13:25:53 +0530] "Data 11"  192.168.0.123 - - [01/Dec/2018:13:25:53 +0530] "Data 12" Referencing equation counter value in custom float caption I have used the float package to create an equation float, eqfloat, so I can add captions to equations. Within the eqfloat I used the equation environment to typeset the math.  I want to keep the right hand arabic numbering within parentheses that is added by the equation environment but I also would like the eqfloat caption below the equation to use the same number as the equation environment.  The following code achieves this by making the eqfloat use the same counter as the equation environment and then manually adjusting the equation numbering within each eqfloat.   Is there a better way to make the eqfloat caption reference the current value of the equation environment counter?  Is it possible to prevent the custom float environment from increasing the counter and only to reference the current value of the equation counter?  \documentclass[a4paper]{article}  \usepackage[margin=25pt, labelfont=bf]{caption} \usepackage{amsmath, amsfonts, pifont, float, color, url} \usepackage[pdftex, plainpages=false, pdfpagelabels, bookmarks=true]{hyperref}  \newfloat{eqfloat}{h}{eqflts} \floatname{eqfloat}{Equation} \makeatletter \let\c@eqfloat\c@equation \makeatother  \begin{document}     ...     \begin{eqfloat}         \begin{equation}             E = mc^2         \end{equation}         \addtocounter{equation}{-1}         \caption{Equation caption here.}         \label{eq:example}     \end{eqfloat}  \end{document} What's a word/phrase for a player/seducer? I can't seem to remember this particular word/phrase. I'm almost certain it's a two-word phrase. It specifically refers to someone who is skilled with the ladies, ie, someone who knows the tricks of the trade.  Usage: - "Unless you're a X-Y, that's not going to work with her."  Edit :  I'm not looking for 'ladies man', 'casanova', 'womanizer' etc. This phrase refers to someone who's more of a pro and one who is serious about his business. A natural number multiplied by some integer results in a number with only ones and zeros I recently solved a , which says that,     A positive integer can be multiplied with another integer resulting in   a positive integer that is composed only of one and zero as digits.   How can I prove that this is true(currently I assume that it is). Also, is it possible to establish an upper bound on the length(number of digits) of the number generated? Disable RAM stick in Windows 7 I have 2 8gb RAM sticks on my motherboard. One is faulty on some bytes and is giving me BSOD once in a while.  Is it possible to disable one of them without removing it physically? I want to keep it inside the motherboard as I dual boot with Xubuntu and I can block the fauly bits there, and as far as I know, it is impossible to block them in Windows.