What is the difference between :   double x = 10.3; int y; y = (int) x;    // c-like cast notation   And :  double x = 10.3; int y; y = reinterpret_cast&lt;int&gt;(x)
What are the proper uses of:   static_cast dynamic_cast const_cast reinterpret_cast C-style cast (type)value Function-style cast type(value)   How does one decide which to use in which specific cases?
Infinite set and countable subsets Prove that a set $A$ is infinite if and only if $A$ contains a countable subset $C$. I know I have to build a sequence and then I'll get a countable subset, but I don't know how to build that sequence from a infinite set. How many characters have appeared in both Marvel and DC comics? The  (the character from Guardians of the Galaxy) says that she has appeared in both Marvel comics as Mantis and DC comics as Willow because her creator "took her with him".     After leaving Marvel Comics, writer Steve Englehart carried Mantis' tale through two other companies before returning to Marvel. In DC Comics' Justice League of America #142, she appears as Willow. Asked where she came from, Willow replies, "This one has come from a place she must not name, to reach a place no man must know." (Mantis refers to herself as "this one").   Are there any other examples of a character appearing in both Marvel and DC comics?  Especially if it's because the original creator has switched companies but still wants to utilize the same character, even under a different name? Breaking single polygon into multiple polygons? I created voronoi polygons after which I dissolved them on the basis of one attribute. Now there are cases where in for one single attribute "abc" I have3 polygons at different places with same object id. I would like to break these into 3 polygons as they are at different locations.  Is there any tool in ArcGIS Desktop or QGIS which can help me in doing that? How to avoid using sudo when working in /var/www? I want to stop having to use sudo everytime I work in /var/www. How can I do that? I simply want to put all of my sites into this directory and work with them without too much pain. When $d$ is in $\mathbb{Z}$, $\mathbb{Z}[\sqrt{d}] = \{a_0 + a_1 \sqrt{d} \mid a_0, a_1 \in \mathbb{Z}\}$  However, when $d$ is in $\mathbb{Q} \setminus \mathbb{Z}$, I cannot prove it.  Of course, when I see an example, I can understand that this is not a finitely generated abelian group, but I want to know the proof in general. How exactly do I install Minecraft Mods and what is Forge? Durrett Example 1.9 - Pairwise independence does not imply mutual independence? The example in question is from Rick Durrett's "Elementrary Probability for Applications", and the setup is something like this:     Let $A$ be the event "Alice and Betty have the same birthday", $B$ be the event "Betty and Carol have the same birthday", and $C$ be the event "Carol and Alice have the same birthday".   Durrett goes on to demonstrate that each pair is independent, since for example,   $P(A \cap B) = P(A)P(B)$.   However, he concludes that $A, B$, and $C$ are not independent, since   $P(A \cap B \cap C) = \frac{1}{365^2} \neq \frac{1}{365^3} = P(A)P(B)P(C)$.  I understand the reasoning here, and that one can generally show that arbitrary events $X$ and $Y$ are not independent by showing that $P(X\cap Y) \neq P(X)P(Y)$.   I am a little new to probability, though, and don't understand why exactly $P(A \cap B \cap C) = \frac{1}{365^2}$.   My progress so far:   I do see why $P(A) = P(B) =P(C) = \frac{1}{365}$, and thus why $P(A)P(B)P(C) = \frac{1}{365^3}$.  It seems like the sample space $\Omega = \{ (a, b, c) \mid a,b,c \in [365] \}$ -- i.e., all of the possible triples of numbers from 1 to 365, where 1 denotes January 1st, 2 denotes January 2nd, etc. From that, I can conclude $|\Omega| = 365^3$, but I'm not sure where to go from here.   It seems like once a single birthday is chosen, the rest are completely determined if they're all equal to each other - is this a good direction to go in? What's the purpose of two capacitors in parallel? What's the purpose of the two capacitors in parallel on each side of the regulator in      I've seen similar setups in other similar circuits and can guess that it's related to one being polarized an one not, but I don't really understand what's going on there. What is the difference between "thee" and "thou"? Evaluate $\lim\limits_{x\to 1}\frac{\sqrt x-x^2 }{1-\sqrt x}$ I'm in a freshmen level physics class now, so I don't know much, but something I heard today intrigued me. My TA was talking about how at the research facility he worked at, they were able to accelerate some certain particle to "99.99% the speed of light". I said why not 100%, and I didn't quite understand his explanation, but he said it wasn't possible. This confused me. Since the speed of light is a finite number, why can we go so close to its speed but not quite?  Edit: I read all the answers, and I think I'm sort of understanding it. Another silly question though: If we are getting this particle to 99.99% the speed of light by giving it some sort of finite acceleration, and increasing it more and more, why cant we increase it just a little more? Sorry I know this is a silly question. I totally accept the fact we cant reach 100%, but I'm just trying to break it down. If we've gotten so close by giving it larger and larger acceleration every time, why cant we just supply it with more acceleration? And how much of a difference is there between 99.99% the speed of light, and the speed of light? (I'm not really sure if "difference" is a good word to use, but hopefully you get what I'm asking). How do I remove a summoned Ender Dragon with no AI? So I used the command /summon EnderDragon ~ ~ ~ {NoAI:1} so that I would have an Ender Dragon that would just sit there.    I then wanted to get rid of it, but doing /killall EnderDragon didn't work, neither did /killallnpc, and I can't seem to do any damage, even with a diamond sword and maximum strength using commands.    I'm not sure why I can't get rid of it; I think it's because the dragon has no AI, but I need to get rid of it somehow, any ideas? What are the basis for co-countable and co-finite topologies Seeking Symbology for Interactive Mapping? When a user clicks on a map what should they expect to see?   I would say a symbol for where they clicked.  A pushpin seems to be the most accepted icon for generic data. Google has pushed the upside down tear drop.   What are other ideas/options and is there a place for finding professional gis oriented icon packs?  I ended up creating this,     This just popped up from the guys at map box. Clean In US hotels, what happens if you skip checkout and just leave the hotel? Every time I check out of a hotel, they ask me if my stay went fine, let me review my incidental charges and ask if they should charge the credit card used to check in.   But what if I simply walk out of the hotel without formally "checking out"? They have my credit card on file and these days you don't even have to return your room key if you want to keep a souvenir. Would it be rude and create more work for hotel employees?  The question arose after spending 15 minutes in the check out queue at a major US hotel. Divisibility by 7 rule, and Congruence Arithmetic Laws I have seen other criteria for divisibility by 7. Criterion described below present in the book Handbook of Mathematics for IN Bronshtein (p. 323) is interesting, but could not prove it. Let $n = (a_ka_{k-1}\ldots a_2a_1a_0)_{10} = \displaystyle{\sum_{j=0}^{k}}a_{k-j}10^{k-j}$. The expression $$ Q_{3}^{\prime}(n) = (a_2a_1a_0)_{10} - (a_5a_4a_3)_{10} + (a_8a_7a_6)_{10} -\ldots  $$ are called alternating sum of the digits of third order of $n$. For example,  $$ Q_{3}^{\prime}(123456789) = 789-456+123=456 $$ Proposition: $7 | n \ \Leftrightarrow \ 7 | Q_{3}^{\prime}(n)$.  proof. ??  Thanks for any help. Let me start this with : Very long "About me" text squeezes both the left side (flair) and the right side (the section with location, GitHub link, etc.)  Now, the reverse thing has happened:         put a long text in their "location", and it causes the right section to be overly extended, effectively squeezing the About Me section.  When will the squeezing game end? The  asks about functions $f \colon \mathbb R \to \mathbb R$ such that $$f(x+y)=f(x)+f(y).$$ It is a very well-known functional equation, which appears in various areas of mathematics ranging from exercises in freshman classes to constructing useful counterexamples for some advanced questions. Solutions of this equation are often called . Also a few other equations related to this equation are often studied. (Equations which can be easily transformed to Cauchy functional equation or can be solved by using similar methods.) Is there some overview of basic facts about Cauchy equation and related functional equations - preferably available online? How to convert milliseconds into human readable form? I need to convert an arbitrary amount of milliseconds into Days, Hours, Minutes Second.  For example: 10 Days, 5 hours, 13 minutes, 1 second. Where can I get the original Unix?