I am creating a library function include a custom deque and dequeNode class. The project is able to build but when referenced in another project, deque is an undefined external.  While trying to find the issue I also put the class files inside the same project and tried to run without going through the lib file and the same issue occured. It seems that the compiler is unable to find the implementation of the class files?  //deque.cpp #include &lt;cstdio&gt; #include &lt;iostream&gt; #include "deque.h"  template&lt;class T&gt; deque&lt;T&gt;::deque() {     // }  template&lt;class T&gt; deque&lt;T&gt;::~deque() {     // }  template&lt;class T&gt; void deque&lt;T&gt;::addToEnd(T data) {     // }  template&lt;class T&gt; void deque&lt;T&gt;::addToBeg(T data) {     // }  template&lt;class T&gt; void deque&lt;T&gt;::insert(int pos, T data) {     // }  template&lt;class T&gt; void deque&lt;T&gt;::remove(int pos) {     // }  template&lt;class T&gt; T deque&lt;T&gt;::getEnd() {     return T(); }  template&lt;class T&gt; T deque&lt;T&gt;::getBeg() {     return T(); }  template&lt;class T&gt; T deque&lt;T&gt;::get(int pos) {     return T(); }   //deque.h #pragma once  #include "dequeNode.h"  template &lt;class T&gt; class deque { private:     dequeNode&lt;T&gt;* head;     dequeNode&lt;T&gt;* tail; public:     int size; public:     deque();     ~deque();      void addToEnd(T data);     void addToBeg(T data);     void insert(int pos, T data);     void remove(int pos);      T getEnd();     T getBeg();     T get(int pos); };   dequeNode.h &amp; dequeNode.cpp are not included because I do not believe they are part of the issue.  tldr; Getting unresolved external but expecting .lib file containing the implentation of the header file class.
Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)
Why *not* parse `ls` (and what to do instead)? When to use IMG vs. CSS background-image? In what situations is it more appropriate to use an HTML IMG tag to display an image, as opposed to a CSS background-image, and vice-versa?  Factors may include accessibility, browser support, dynamic content, or any kind of technical limits or usability principles. Was the Wookiee language fully designed or is it just random emotionally-relevant sounds? We know that some of the other Star Wars languages were fairly well developed by the movie's creators, in terms of vocabulary, grammar, etc.  Was the Wookiee language designed in this level of detail or did they just try to put together sounds that made sense emotionally? Hi I want to try Ubuntu 20.04 without installing it due to some driver issues in my laptop. But I already have 2 OS ( Windows 10 and Ubuntu 20.04 [Dualboot] ), so will trying Ubuntu mess with the already installed Operating systems? And I know how to make live usb and booting from it but don't know how to exit it and then bring my laptop back to normal. Tried finding procedure on internet but reliable results are not found. What hardware does Ubuntu Touch support? How to get world-space matrix of any pose bone? Is there a command for getting world-space matrix of pose bones, same as obj.matrix_world for objects? I found pose_bone.matrix, but it gives weird result for me. Wi-Fi not working on Lenovo ThinkPad E570 (Realtek RTL8821CE) .NET String.Format() to add commas in thousands place for a number I want to add a comma in the thousands place for a number.     String.Format()? I do love to listen to music while watching text YouTube videos, but I can't because YouTube can't be muted.  I use the respect audio focus in  Music Player.  I have tried App Volume Control but it did nothing! Having recently switched to Google Chrome, I was wondering what files and directories I should be including in my backups to make sure that bookmarks and history are included.  Along the same lines, is there a process to restore these settings on a new install?  This is on Windows Vista. Remove only the commas present within the double quotes In a text file, I want to remove , (commas) and also the " (quotes) (only if the double quotes  contains  numbers separated by commas).  56,72,"12,34,54",x,y,"foo,a,b,bar"   Expected ouput  56,72,123454,x,y,"foo,a,b,bar"   Note: I show the above line just as an example. My text file contains many lines like above and the numbers separated by commas present within the double quotes should vary. That is,  56,72,"12,34,54",x,y,"foo,a,b,bar" 56,92,"12,34",x,y,"foo,a,b,bar" 56,72,"12,34,54,78,76,54,67",x,y,"foo,a,b,bar" 56,72,x,y,"foo,a,b,bar","12,34,54" 56,72,x,y,"foo,a,b,bar","12,34,54","45,57,84,92","bar,foo"   Expected output:  56,72,123454,x,y,"foo,a,b,bar" 56,92,1234,x,y,"foo,a,b,bar" 56,72,12345478765467,x,y,"foo,a,b,bar" 56,72,x,y,"foo,a,b,bar",123454 56,72,x,y,"foo,a,b,bar",123454,45578492,"bar,foo"   There a n number of numbers present within the double quotes separated by commas. And also leave the double quotes which contains characters as it is.  I love sed text processing tool. I'm happy if you post any sed solution for this. public static map&lt;id,RecordType&gt; MapRecordtype = new Map&lt;id,RecordType&gt;([SELECT id, DeveloperName FROM RecordType where sobjecttype ='move__c' and                                         Developername in('Assignment','Draft','Domestic_Draft','LTST_Draft','MX_Domestic','MX_Domestic_draft','Termination','International_Relo','Localization','J1',                                        'Back_To_Back','Repatriation','PAM','US_Domestic_Relo','CHN_Domestic_Relo','CHN_Domestic_Draft')])   Can we write schema for above query? I am trying to find a book (young adult) where the devil is the protaganist, and other gods appear as characters I believe it was written by a teenager, and might have a sequel.   It has been many years since I read it, but I believe it had the devil acting like a regular human. He wasn't evil. I think it incorporated a lot of (gods/characters) norse, roman, Christian, and pagan. How does one create a custom application launcher for Wine installed apps? Can I make any injective function bijective by patching the codomain? Mac turns off randomly and has lines on screen For some reason my iMac keeps turning off around 5 to 10 minutes into boot.  Also just recently it turns on but has shaded lines going down the screen. I have not installed any weird programs and i have not used it in around 3 months.   Any ideas on what the issue is, i don't have any other information about the issue besides whats happening when i use it.  The image i'm showing you was found on google but this looks exactly like mine does.  The model of my imac is the late 2011 model. Equivalent definition of metric compatibility for a connection: what does $\nabla g$ mean? So the definition I know for metric compatibility is:  $$Xg(Y,Z)=g(\nabla_XY,Z)+g(Y,\nabla_XZ),$$   which make sense, as $g(Y,Z)$ is a smooth function from the manifold to reals and we think of $X$ as a derivation. So now I read this apparent equivalent definition that says $\nabla g=0$. Can someone explain what this means? How can I do $\nabla$ of $g$ I thought $g_p$ is an element of $T_p^*M\otimes T_p^*M$ at every point. Furthermore after you explain the meaning of this can you show me that these two definitions are indeed equivalent? How do I use Linq to obtain a unique list of properties from a list of objects? I'm trying to use Linq to return a list of ids given a list of objects where the id is a property. I'd like to be able to do this without looping through each object and pulling out the unique ids that I find.  I have a list of objects of type MyClass and one of the properties of this class is an ID.  public class MyClass {   public int ID { get; set; } }   What I want to do is write a Linq query to return me a list of those Ids  How do I do that given an IList&lt;MyClass&gt; such that it returns an IEnumerable&lt;int&gt; of the ids?  I'm sure it must be possible to do it in one or two lines using Linq rather than looping through each item in the MyClass list and adding the unique values into a list.  Any help in creating an elegant solution would be much appreciated! Why is there a mismatch between size reported by LVM and the size reported by df -h? I'm new to LVM and have been very confused by this:  I am transfering a large file to a partition that I thought had about 1.5 terabytes of space on it.  Near the end of the transfer, rsync exits with an error claiming that the partition is full.  I investigate and find the following:  $ sudo lvm lvs   LV        VG     Attr   LSize   Origin Snap%  Move Log Copy%  Convert   home      system -wi-ao  97.66G                                         log       system -wi-ao  48.81G                                         log.audit system -wi-ao   9.75G                                         root      system -wi-ao 341.59G                                         swap      system -wi-ao   4.88G                                         temp      system -wi-ao  97.66G                                         var       system -wi-ao   1.46T     This seems to imply that /var (the partition that I'm transfering to, has the amount of storage I expect.  However, then I see:  $ sudo df -h Filesystem            Size  Used Avail Use% Mounted on /dev/mapper/system-root                       331G  1.3G  313G   1% / /dev/mapper/system-temp                        95G  188M   90G   1% /tmp /dev/mapper/system-var                        95G   90G     0 100% /var /dev/mapper/system-home                        95G  188M   90G   1% /home /dev/mapper/system-log                        48G  264M   45G   1% /var/log /dev/mapper/system-log.audit                       9.5G  340M  8.7G   4% /var/log/audit /dev/sda1              99M   25M   70M  26% /boot tmpfs                 8.0G     0  8.0G   0% /dev/shm   I'm guessing this has something to do with the volume being resized at some point.  While I have reliable backups, I'd rather not interrupt services for the time it will take to get the backup and restore.  Thus, is there anyway to make the filesystem seen by the OS match the space available according to lvm without losing data? I'm a student who uses the laptop all the time and I have a problem with Wifi on the laptop. I don't really know what it is. I can describe the problem tho. For example, i closed my laptop last night, so it goes in suspend mode. I turn it on this morning and my wifi doesn't want to connect until I restart the laptop. It says that it's connecting and in Wifi settings the circle animation is spinning, turning Wifi off and on doesn't do anything. Here's what happens when I check to see my network info: sudo lshw -C network   *-network                         description: Wireless interface        product: Wireless 3160        vendor: Intel Corporation        physical id: 0        bus info: pci@0000:02:00.0        logical name: wlp2s0        version: 83        serial: 00:1e:64:e6:1c:93        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless        configuration: broadcast=yes driver=iwlwifi driverversion=5.4.0-52-generic firmware=17.3216344376.0 ip=192.168.0.14 latency=0 link=yes multicast=yes wireless=IEEE 802.11        resources: irq:129 memory:df100000-df101fff   *-network        description: Ethernet interface        product: RTL810xE PCI Express Fast Ethernet controller        vendor: Realtek Semiconductor Co., Ltd.        physical id: 0        bus info: pci@0000:03:00.0        logical name: enp3s0        version: 07        serial: f8:ca:b8:52:72:49        capacity: 100Mbit/s        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation        configuration: autonegotiation=on broadcast=yes driver=r8169 firmware=rtl8106e-1_0.0.1 06/29/12 latency=0 link=no multicast=yes port=MII        resources: irq:17 ioport:d000(size=256) memory:df000000-df000fff memory:d0000000-d0003fff  Also I have to mention that my Linux is doublebooted alongside Windows 10, but I don't think that makes any difference. Help would be much appreciated, I wouldn't want to miss my classes because of this hahah Thanks!