for non-template class, I can use forward declaration in the header file. But it gave me error when I use it in the template class.  I have to include the header file, I would like to know the reason.  class Pu;  template &lt;typename T&gt; class Pt() {      void test(Pu&lt;T&gt; u); }
I am looking for the definition of when I am allowed to do forward declaration of a class in another class's header file:  Am I allowed to do it for a base class, for a class held as a member, for a class passed to member function by reference, etc. ?
Use a partitioned live usb I have a USB device and i'm trying to create it in a way that it has 2 partitions: one for a live linux disc and the other for document storage.  I created the partitions using gparted and and set a boot flag to the one I want to use as the live disc. Now, I have a usb like this:  Disk /dev/sdc: 14.6 GiB, 15623782400 bytes, 30515200 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xc3072e18  Device     Boot   Start      End  Sectors  Size Id Type /dev/sdc1       8439808 30515199 22075392 10.5G 83 Linux /dev/sdc2  *      51200  8439807  8388608    4G  b W95 FAT32   I then used dd to flash an Ubuntu iso to /dev/sdc2  sudo dd if=/dev/shm/ubuntu-17.04-desktop-amd64.iso of=/dev/sdc2 bs=4M   When the disc is flashed onto the usb drive, I try to boot from my laptop and it shows "Operating system not found". When i try to use qemu/kvm, it shows a kernel panic like this:    How would I be able to do this properly? I have a question about the following text:     Last week Alex Knapp at Forbes published an article criticizing my Nikola Tesla comic. I don't normally respond to these kinds of thing, but since it's' Forbes I figured a proper response was in order.    I would rather say "this kind of things" rather than the version in the text above. Clerical mistake in UK visa application: should I make a pen-and-ink correction or electronically edit the PDF? I've gone through all similar questions but I believe my specific question doesn't have an answer yet.  I've applied for a Standard Visitor visa. After I completed the application, made an appointment and paid the fee, I noticed that the way I spelled my name on the application differs from how it is spelled in the passport by 1 letter (this is partially because of myself being an idiot, but mainly because my new passport has an incorrect transliteration of my name, whereas my old passport and any other document in my life has the correct one).  So here are the options I see:   Print the application and make a pen-and-ink correction with a black ballpoint pen by crossing the printed name/letter and writing the correct one - as answers to other similar questions suggests. Edit the PDF electronically and print it so that there are no visible corrections. However, as the form is saved at their end, there will be a discrepance between the printed form and saved form with no visible signs of correction.   Which way has better chance for me to have my application accepted?  Also (probably doesn't matter much but still): if it's the pen-and-ink correction, is it better to cross-out the whole name or only the wrong letter? If $f$ is continuous, then there exists $x+\frac{1}{n}\in[0,1]$ and $f\left(x+\frac{1}{n}\right)=f(x)$ Let $f:[0,1]\to \mathbb{R}$ is continuous, such that $f(0)=f(1)$. For each $n\in\mathbb{N}$, prove that $\exists x\in [0,1]$ such that $x+\dfrac{1}{n}\in[0,1]$ and $f\left(x+\dfrac{1}{n}\right)=f(x)$.   My approach: The interval $[0,1]$ is connected, then if $f$ is continuous, we have $f([0,1])\subset\mathbb{R}$ is a interval. And I suppose that, I can define a closed path such that $f(0)=f(1)$. Any hint pls, Why is the ROC curve two-dimensional instead of three-dimensional? See the revision history on , where the  tag was edited in (and subsequently edited out after I started this discussion).  I think, by adding this tag, you're making assumptions about the OP which they could find a little bit offensive.  Particularly with this question, there's no mention of the level of PHP knowledge — it's more a math question than it is a programming question. Someone could be excellent at a particular language whilst not being particularly great at math, so isn't it a bit insulting to make the assumption they're a beginner? It's also interesting to note  tag, which currently stands at 7,784 on SO.  Compare this to , which only has 18 questions, most of them being &quot;discussiony.&quot;  Why do users retag questions as &quot;beginner&quot; but not &quot;expert&quot;? UPDATE, , .  Related   (thanks @Ralph) This might be a stupid question, but nonetheless, it has been bothering me.  If you take a photon, make it go through some atoms in a solid, liquid or whatever, then you have the chance of this photon being absorbed by an electron, and thereby exciting the electron. This requires the photon to have enough energy to actually excite the electron to another energy level.  My question is then: How does the photon know if it has enough energy or not? Do they interact very quickly to determine if it's okay or not, or is it just something it "knows?" Do continuous linear functions between Banach spaces extend? I need to convert some files to PDF and then attach them to an email.  I'm using Pear Mail for the email side of it and that's fine (mostly--still working out some issues) but as part of this I need to create temporary files.  Now I could use the  function but it sounds like it creates a file on the filesystem, which isn't what I want.  I just want a name in the temporary file system (using ) that won't clash with someone else running the same script of the same user invoking the script more than once.  Suggestions? i have a usb wifi adapter Tp-Link model: wn725n  it works very well on windows but i can't find any drivers for linux/ubuntu i tried everything online but nothing work so far  i'm using   Ubuntu 14.04.3 LTS  3.19.0-28-generic  laptop: hp probook 4540s  can you please help me install this adapter? What are the various physical mechanisms for energy transfer to the photon during blackbody emission? Why are some of my screen-recording/capturing/sharing applications (or app features) not working in Ubuntu 17.10 (and later releases)? After upgrading to Ubuntu 17.10 I noticed some of my screencasting applications are not working, for example screencasting tools like SimpleScreenRecorder and vokoscreen. ()  Also I noticed features like screenshot from GIMP is not working properly, producing blank screenshots (). Shutter too is producing glitchy screenshots ().  Screen-sharing option on Skype is also not working ().  The issue occurs sometimes on later Ubuntu releases too.  Why is this happening and how do I fix this? Identify a book with a social engineering theme I originally read this book in the mid- to late '70s.   The premise was a bureaucracy whose job it was to manipulate events in human history by making the smallest possible change that would effect the desired outcome. Not time cops in the sense of going after law breakers.  The intent was to maintain a policy of non-interference as much as possible but when interference was warranted then to make the least possible change and to do so invisibly.  For example, they might take someone's keys off the dresser and put them just out of sight underneath the dresser where they plausibly might have fallen.  The subject would never know of the manipulation but would then be delayed getting out of the house and the ripples grew from there to avert a war or otherwise affect events on a large scale.  After reading that, whenever I would lose something - especially in an improbable way such as dropping a screw at my feet and then finding it on the other side of the room half an hour later - I would take some consolation in the thought that I had just averted some global catastrophe.  I was pretty scatterbrained as a kid (we call that ADHD nowadays) so I experienced this a lot.  Given that I've spent so much time pondering the ideas from the book, I'd love to re-read it. Here is my proof, I would appreciate it if someone could critique it for me:  To prove this statement true, we must proof that the two conditional statements ("If $\mathcal{P}(A)⊆ \mathcal{P}(B)$, then $A⊆B$," and, If $A⊆B$, then $\mathcal{P}(A)⊆ \mathcal{P}(B)$) are true.    Contrapositive of the first statement: If $A \nsubseteq B$, then $\mathcal{P}(A) \nsubseteq \mathcal{P}(B)$  If $A \nsubseteq B$, then there must be some element in $A$, call it $x$, that is not in $B$: $x \in A$, and $x \notin B$. Since $x \in A$, then $\{x\} \in \mathcal{P}(A)$; moreover, since $x \notin B$, then $\{x\} \notin \mathcal{P}(B)$, which proves that, if $A \nsubseteq B$, then $\mathcal{P}(A) \nsubseteq \mathcal{P}(B)$. By proving the contrapositive true, the original proposition must be true.    To prove the second statement true, I would implement nearly the same argument, so that isn't necessary to write. So, does this proof seem correct? Also, was the contrapositive necessary? Or is there another way to prove the initial statement? In sketchup you can move an object based on two points. This makes it very easy to align a vertex in one object to vertex in another object. Here is an example:    I want to know how to do this in Blender. It seems that Translate can't align vertexs How can i get currency symbols from currency code in iphone? Obtaining client IP address in WCF 3.0 How to get rid of navigation symbols in beamer? Android: Making Https Request We have Godaddy's Dedicated server. but we are facing problems with this server. after on 400-500 active users server randomly timeout or kill users. we this it's error with IIS. We did conversation with some server experts they said there is some issue with IIS. but nobody can resolve this issue. i share a screen shoot of analytic of active users. Please help us.