Search Results

Search found 14000 results on 560 pages for 'include guards'.

Page 463/560 | < Previous Page | 459 460 461 462 463 464 465 466 467 468 469 470  | Next Page >

• Howcome some C++ functions with unspecified linkage build with C linkage?

  - by christoffer

  This is something that makes me fairly perplexed. I have a C++ file that implements a set of functions, and a header file that defines prototypes for them. When building with Visual Studio or MingW-gcc, I get linking errors on two of the functions, and adding an 'extern "C"' qualifier resolved the error. How is this possible? Header file, "some_header.h": // Definition of struct DEMO_GLOBAL_DATA omitted DWORD WINAPI ThreadFunction(LPVOID lpData); void WriteLogString(void *pUserData, const char *pString, unsigned long nStringLen); void CheckValid(DEMO_GLOBAL_DATA *pData); int HandleStart(DEMO_GLOBAL_DATA * pDAta, TCHAR * pLogFileName); void HandleEnd(DEMO_GLOBAL_DATA *pData); C++ file, "some_implementation.cpp" #include "some_header.h" DWORD WINAPI ThreadFunction(LPVOID lpData) { /* omitted */ } void WriteLogString(void *pUserData, const char *pString, unsigned long nStringLen) { /* omitted */ } void CheckValid(DEMO_GLOBAL_DATA *pData) { /* omitted */ } int HandleStart(DEMO_GLOBAL_DATA * pDAta, TCHAR * pLogFileName) { /* omitted */ } void HandleEnd(DEMO_GLOBAL_DATA *pData) { /* omitted */ } The implementations compile without warnings, but when linking with the UI code that calls these, I get a normal error LNK2001: unresolved external symbol "int __cdecl HandleStart(struct _DEMO_GLOBAL_DATA *, wchar_t *) error LNK2001: unresolved external symbol "void __cdecl CheckValid(struct _DEMO_MAIN_GLOBAL_DATA * What really confuses me, now, is that only these two functions (HandleStart and CheckValid) seems to be built with C linkage. Explicitly adding "extern 'C'" declarations for only these two resolved the linking error, and the application builds and runs. Adding "extern 'C'" on some other function, such as HandleEnd, introduces a new linking error, so that one is obviously compiled correctly. The implementation file is never modified in any of this, only the prototypes.

  Read the article

• changing the serialization procedure for a graph of objects (.net framework)

  - by pierusch

  Hello I'm developing a scientific application using .net framework. The application depends heavily upon a large data structure (a tree like structure) that has been serialized using a standard binaryformatter object. The graph structure looks like this: <serializable()>Public class BigObjet inherits list(of smallObject) end class <serializable()>public class smallObject inherits list(of otherSmallerObjects) end class ... The binaryFormatter object does a nice job but it's not optimized at all and the entire data structure reaches around 100Mb on my filesystem. Deserialization works too but it's pretty slow (around 30seconds on my quad core). I've found a nice .dll on codeproject (see "optimizing serialization...") so I wrote a modified version of the classes above overriding the default serialization/deserialization procedure reaching very good results. The problem is this: I can't lose the data previosly serialized with the old version and I'd like to be able to use the new serialization/deserialization method. I have some ideas but I'm pretty sure someone will be able to give me a proper and better advice ! use an "helper" graph of objects who takes care of the entire serialization/deserialization procedure reading data from the old format and converting them into the classes I nedd. This could work but the binaryformatter "needs" to know the types being serialized so........ :( modify the "old" graph to include a modified version of serialization procedure...so I'll be able to deserialize old file and save them with the new format......this doesn't sound too good imho. well any help will be higly highly appreciated :)

  Read the article

• base destructor called twice after derived object?

  - by sil3nt

  hey there, why is the base destructor called twice at the end of this program? #include <iostream> using namespace std; class B{ public: B(){ cout << "BC" << endl; x = 0; } virtual ~B(){ cout << "BD" << endl; } void f(){ cout << "BF" << endl; } virtual void g(){ cout << "BG" << endl; } private: int x; }; class D: public B{ public: D(){ cout << "dc" << endl; y = 0; } virtual ~D(){ cout << "dd" << endl; } void f(){ cout << "df" << endl; } virtual void g(){ cout << "dg" << endl; } private: int y; }; int main(){ B b, * bp = &b; D d, * dp = &d; bp->f(); bp->g(); bp = dp; bp->f(); bp->g(); }

  Read the article

• How to invoke make install for one subdirectory of Qt project

  - by chalup

  I'm working on custom library and I wish users could just use it by adding: CONFIG += mylib to their pro files. This can be done by installing mylib.prf file to %QTDIR%/mkspec/features. I've checked out in Qt Mobility project how to create and install such file, but there is one thing I'd like to do differently. If I correctly understood the pro/pri files of Qt Mobility, inside the example projects they don't really use CONFIG += mobility, instead they add QtMobility sources to include path and share the *.obj directory with main library project. For my library I'd like to have examples that are as independent projects as possible, i.e. projects that can be compiled from anywhere once MyLib is compiled and installed. I have following directory structure: mylib | |- examples |- src |- tests \- mylib.pro It seems that the easiest way to achieve what I described above is creating mylib.pro like this: TEMPLATE = subdirs SUBDIRS += src SUBDIRS += examples tests:SUBDIRS += tests And somehow enforce invoking "cd src && make install" after building src. What is the best way to do this? Of course any other suggestions for automatic library deployment before examples compilation are welcome.

  Read the article

• Element Content Versus Attribute for Simple XML Value

  - by MB

  I know the elements versus attributes debate has come up many times here and elsewhere (e.g. here, here, here, here, and here) but I haven't seen much discussion of elements versus attributes for simple property values. So which of the following approaches do you think is better for storing a simple value? A: Value in Element Content: <TotalCount>553</TotalCount> <CelsiusTemperature>23.5</CelsiusTemperature> <SingleDayPeriod>2010-05-29</SingleDayPeriod> <ZipCodeLocation>12203</ZipCodeLocation> or B: Value in Attribute: <TotalCount value="553"/> <CelsiusTemperature value="23.5"/> <SingleDayPeriod day="2010-05-29"/> <ZipCodeLocation code="12203"/> I suspect that putting the value in the element content (A) might look a little more familiar to most folks (though I'm not sure about that). Putting the value in an attribute (B) might use less characters, but that depends on the length of the element and attribute names. Putting the value in an attribute (B) might be more extensible, because you could potentially include all sorts of extra information as nested elements. Whereas, by putting the value inside the element content (A), you're restricting extensibility to adding more attributes. But then extensibility often isn't a concern for really simple properties - sometimes you know that you'll never need to add additional data. Bottom line might be that it simply doesn't matter, but it would still be great to hear some thoughts and see some votes for the two options.

  Read the article

• Consistent HashCode() and Equals() results, but inconsistent TreeMap.containsKey() result

  - by smessing

  I have the following object Node: private class Node implements Comparable<Node>(){ private String guid(); ... public boolean equals(Node o){ return (this == o); } public int hashCode(){ return guid.hashCode(); } ... } And I use it in the following TreeMap: TreeMap<Node, TreeSet<Edge>> nodes = new TreeMap<Node, TreeSet<Edge>>(); Now, the tree map is used in a class called Graph to store nodes currently in the graph, along with a set of their edges (from the class Edge). My problem is when I try to execute: public containsNode(n){ for (Node x : nodes.keySet()) { System.out.println("HASH CODE: "); System.out.print(x.hashCode() == n.hashCode()); System.out.println("EQUALS: "); System.out.print(x.equals(n)); System.out.println("CONTAINS: "); System.out.print(nodes.containsKey(n)); System.out.println("N: " + n); System.out.println("X: " + x); } } I sometimes get the following: HASHCODE: true EQUALS: true CONTAINS: false N: foo X: foo Anyone have an idea as to what I'm doing wrong? I'm still new to all this, so I apologize in advance if I'm overlooking something simple (I know hashCode() doesn't really matter for TreeMap, but I figured I'd include it).

  Read the article

• Powershell: splatting after passing hashtable by reference

  - by user1815871

  Powershell newbie ... I recently learned about splatting — very useful. I ran into a snag when I passed a hash table by reference to a function for splatting purposes. (For brevity's sake — a silly example.) Function AllMyChildren { param ( [ref]$ReferenceToHash } get-childitem @ReferenceToHash.Value # etc.etc. } $MyHash = @{ 'path' = '*' 'include' = '*.ps1' 'name' = $null } AllMyChildren ([ref]$MyHash) Result: an error ("Splatted variables cannot be used as part of a property or array expression. Assign the result of the expression to a temporary variable then splat the temporary variable instead."). Tried this afterward: $newVariable = $ReferenceToHash.Value get-childitem @NewVariable That did work and seemed right per the error message. But: is it the preferred syntax in a case like this? (An oh, look, it actually worked solution isn't always a best practice. My approach here strikes me as "Perl-minded" and perhaps in Powershell passing by value is better, though I don't yet know the syntax for it w.r.t. a hash table.)

  Read the article

• How to create copying items from property values?

  - by Nam Gi VU

  Let's say I have a list of sub paths such as <PropertyGroup> <subPaths>$(path1)\**\*; $(path2)\**\*; $(path3)\file3.txt; </subPaths> </PropertyGroup> I want to copy these files from folder A to folder B (surely we already have all the sub folders/files in A). What I try was: <Target Name="Replace" DependsOnTargets="Replace_Init; Replace_Copy1Path"> </Target> <Target Name="Replace_Init"> <PropertyGroup> <subPaths>$(path1)\**\*; $(path2)\**\*; $(path3)\file3.txt; </subPaths> </PropertyGroup> <ItemGroup> <subPathItems Include="$(subPathFiles.Split(';'))" /> </ItemGroup> </Target> <Target Name="Replace_Copy1Path" Outputs="%(subPathItems.Identity)"> <PropertyGroup> <src>$(folderA)\%(subPathItems.Identity)</src> <dest>$(folderB)\%(subPathItems.Identity)</dest> </PropertyGroup> <Copy SourceFiles="$(src)" DestinationFiles="$(dest)" /> </Target> But the Copy task didn't work. It doesn't translate the *** to files. What did I do wrong? Please help!

  Read the article

• Segmentation fault in C recursive Combination (nCr)

  - by AruniRC

  PLease help me out here. The program is supposed to recursively find out the combination of two numbers. nCr = n!/ (r!(n-r)! ). I'm getting this error message when i compile it on GCC. Here's what the terminal shows: Enter two numbers: 8 4 Segmentation fault (Program exited with code:139) The code is given here: #include<stdio.h> float nCr(float, float, float); int main() { float a, b, c; printf("Enter two numbers: \n"); scanf("%f%f", &a, &b); c = nCr(a, b, a-b); printf("\n%.3f", c); return 0; } float nCr(float n, float r, float p) { if(n<1) return (1/(p*r))*(nCr(1, r-1, p-1)); if(r<1) return (n/(p*1))*(nCr(n-1, 1, p-1)); if(p<1) return (n/r)*(nCr(n-1, r-1, 1)); return ( n/(p*r) )*nCr(n-1, r-1, p-1); }

  Read the article

• merge my code with Ajax code>>> problem

  - by sandy

  I want to help me In the following link i found nice code in Ajax http://www.w3schools.com/php/php_ajax_livesearch.asp I want to link my code with the code you see in the link above and replace dropdown list How can I do it for I could not where is it change in code even my code work as Ajax ?? I wish .... I wish .... I wish any somebody can help me <?php include ("connect.php"); print_r($_POST['sector_list']); $member_id = intval($_POST['sector_list']); if($member_id == 0) { // Default choice was selected } else { $res = mysql_query("SELECT * FROM members WHERE MemberID = $member_id LIMIT 1"); if(mysql_num_rows($res) == 0) { // Not a valid member } else { // The member is in the database } } ?> <form method="POST" action=<?php echo $_SERVER["PHP_SELF"]; ?> > <input type="hidden" name="sector" value="sector_list"> <select name="sector_list[]" class="inputstandard" multiple="multiple"> <option size ="40" value="default">send to </option> <?php $result = mysql_query('SELECT * from members') or die(mysql_error()); while ($row = mysql_fetch_assoc($result)) { echo '<option value="' . $row['MemberName'] . '">' . $row['MemberName']. '</option>'; } ?> <input type ="submit" name ="go" value = "go" > </select> </form>

  Read the article

• Google App Engine datastore encoding?

  - by sernaferna

  I'm using the GAE datastore for a Java application, and storing some text that will be in numerous languages. In my servlet, I'm first checking to see if there's any data in the data store, and, if not, I'm creating some, similar to the following: ArrayList<Lang> list = new ArrayList<Lang>(); list.add(new Lang("EN", "English", 1)); list.add(new Lang("ES", "Español", 0)); //more languages here... PersistenceManager pm = PMF.get().getPersistenceManager(); for(Lang l : list) { pm.makePersistent(l); } Since this is using JDO, I guess I should include the relevent parts of the Lang class too: @PersistenceCapable public class Lang { @PrimaryKey private String code; @Persistent private String name; @Persistent private int popularity; // getters & setters & constructors... } However, the non-ASCII characters are giving me grief. I've set my Eclipse project to use the UTF-8 encoding instead of the default Cp1252, so I think I'm okay from that perspective, but when I use the App Engine Data Viewer to look at my data, that Español entry becomes Español, and when I click on it to view it, I get a 500 Server Error. (There are some other entries with right-to-left text that don't even show up in the Data Viewer at all, but one problem at a time...) Is there anything special I can do in my code to set the character encoding, or specify to GAE that the data I'm storing is UTF-8? Or is the problem on the Eclipse side, and is there something I should be doing with my Java code?

  Read the article

• No grammar constraints (DTD or XML schema) detected for the document.

  - by fastcodejava

  I have this dtd : http://fast-code.sourceforge.net/template.dtd But when I include in an xml I get the warning : No grammar constraints (DTD or XML schema) detected for the document. The xml is : <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE templates PUBLIC "//UNKNOWN/" "http://fast-code.sourceforge.net/template.dtd"> <templates> <template type="type"> <description>Some</description> <variation></variation> <variation-field></variation-field> <allow-multiple-variation></allow-multiple-variation> <class-pattern></class-pattern> <getter-setter>setter</getter-setter> <allowed-file-extensions>java</allowed-file-extensions> <number-required-classes>1</number-required-classes> <template-body> <![CDATA[ Some Data ]]> </template-body> </template> </templates> Any clue?

  Read the article

• NSNotification vs. Delegate Protocols?

  - by jr

  I have an iPhone application which basically is getting information from an API (in XML, but maybe JSON eventually). The result objects are typically displayed in view controllers (tables mainly). Here is the architecture right now. I have NSOperation classes which fetch the different objects from the remote server. Each of these NSOperation classes, will take a custom delegate method which will fire back the resulting objects as they are parsed, and then finally a method when no more results are available. So, the protocol for the delegates will be something like: (void) ObjectTypeResult:(ObjectType *)result; (void) ObjectTypeNoMoreResults; I think the solution works well, but I do end up with a bunch of delegate protocols around and then my view controllers have to implement all these delegate methods. I don't think its that bad, but I'm always on the lookout for a better design. So, I'm thinking about using NSNotifications to remove the use of the delegates. I could include the object in the userInfo part of the notification and just post objects as received, and then a final event when no more are available. Then I could just have one method in each view controller to receive all the data, even when using multiple objects in one controller.† So, can someone share with me some pros/cons of each approach. Should I consider refactoring my code to use Events rather then the delegates? Is one better then the other in certain situations? In my scenario I'm really not looking to receive notifications in multiple places, so maybe the protocol based delegates are the way to go. Thanks!

  Read the article

• Function pointers to member functions

  - by Jacob

  There are several duplicates of this but nobody explains why I can use a member variable to store the pointer (in FOO) but when I try it with a local variable (in the commented portion of BAR), it's illegal. Could anybody explain this? #include <iostream> using namespace std; class FOO { public: int (FOO::*fptr)(int a, int b); int add_stuff(int a, int b) { return a+b; } void call_adder(int a, int b) { fptr = &FOO::add_stuff; cout<<(this->*fptr)(a,b)<<endl; } }; class BAR { public: int add_stuff(int a, int b) { return a+b; } void call_adder(int a, int b) { //int (BAR::*fptr)(int a, int b); //fptr = &BAR::add_stuff; //cout<<(*fptr)(a,b)<<endl; } }; int main() { FOO test; test.call_adder(10,20); return 0; }

  Read the article

• How to Set up Virtual Static Subdomain

  - by Chip D

  Given current rewrite rules at http://www.example.com/: Options +FollowSymlinks +Includes RewriteEngine on RewriteBase / RewriteCond %{HTTP_HOST} !^www\.example\.com [NC] RewriteCond %{HTTP_HOST} !^$ RewriteRule ^/?(.*) http://www.example.com/$1 [L,R,NE] # Remove all "index.html"s. RewriteCond %{THE_REQUEST} \ /(.+/)?index\.html(\?.*)?\ [NC] RewriteRule ^(.+/)?index\.html$ /%1 [R=301,L] # Remove all "index.php"s. RewriteCond %{THE_REQUEST} \ /(.+/)?index\.php(\?.*)?\ [NC] RewriteRule ^(.+/)?index\.php$ /%1 [R=301,L] I'm attempting to serve some site assets (.png|.ico|.jpg|.gif|.css|.js) from a static subdomain like http://static.example.com which my Apache 1.3 shared host (GoDaddy) has mapped to a subdirectory for file management (http://www.example.com/static/). Currently these assets live in same-site subdirectories such as images/, js/, css/, etc. (1) Something...maybe the "+www" rewrite rule?...is not letting me access the subdomain. Is this likely caused by my rewrite rules above, or do I need to set up DNS changes with the host to enable access to the subdirectory, in addition to changing the rewrite rules? (2) Do I have to move those assets to that subdirectory and change all references sitewide? Would that perform the fastest? (3) Or can .htaccess make this much easier? (4) Should my first rewrite rule above include L,R=301,NE instead of [L,R,NE]?

  Read the article

• MySQL query puzzle - finding what WOULD have been the most recent date

  - by Hank

  I've looked all over and haven't yet found an intelligent way to handle this, though I feel sure one is possible: One table of historical data has quarterly information: CREATE TABLE Quarterly ( unique_ID INT UNSIGNED NOT NULL, date_posted DATE NOT NULL, datasource TINYINT UNSIGNED NOT NULL, data FLOAT NOT NULL, PRIMARY KEY (unique_ID)); Another table of historical data (which is very large) contains daily information: CREATE TABLE Daily ( unique_ID INT UNSIGNED NOT NULL, date_posted DATE NOT NULL, datasource TINYINT UNSIGNED NOT NULL, data FLOAT NOT NULL, qtr_ID INT UNSIGNED, PRIMARY KEY (unique_ID)); The qtr_ID field is not part of the feed of daily data that populated the database - instead, I need to retroactively populate the qtr_ID field in the Daily table with the Quarterly.unique_ID row ID, using what would have been the most recent quarterly data on that Daily.date_posted for that data source. For example, if the quarterly data is 101 2009-03-31 1 4.5 102 2009-06-30 1 4.4 103 2009-03-31 2 7.6 104 2009-06-30 2 7.7 105 2009-09-30 1 4.7 and the daily data is 1001 2009-07-14 1 3.5 ?? 1002 2009-07-15 1 3.4 && 1003 2009-07-14 2 2.3 ^^ then we would want the ?? qtr_ID field to be assigned '102' as the most recent quarter for that data source on that date, and && would also be '102', and ^^ would be '104'. The challenges include that both tables (particularly the daily table) are actually very large, they can't be normalized to get rid of the repetitive dates or otherwise optimized, and for certain daily entries there is no preceding quarterly entry. I have tried a variety of joins, using datediff (where the challenge is finding the minimum value of datediff greater than zero), and other attempts but nothing is working for me - usually my syntax is breaking somewhere. Any ideas welcome - I'll execute any basic ideas or concepts and report back.

  Read the article

• Good Replacement for User Control?

  - by David Lively

  I found user controls to be incredibly useful when working with ASP.NET webforms. By encapsulating the code required for displaying a control with the markup, creation of reusable components was very straightforward and very, very useful. While MVC provides convenient separation of concerns, this seems to break encapsulation (ie, you can add a control without adding or using its supporting code, leading to runtime errors). Having to modify a controller every time I add a control to a view seems to me to integrate concerns, not separate them. I'd rather break the purist MVC ideology than give up the benefits of reusable, packaged controls. I need to be able to include components similar to webforms user controls throughout a site, but not for the entire site, and not at a level that belongs in a master page. These components should have their own code not just markup (to interact with the business layer), and it would be great if the page controller didn't need to know about the control. Since MVC user controls don't have codebehind, I can't see a good way to do this. I've searched previous SO questions, and have yet to find a good answer. Options so far In an attempt to avoid turning the comments section into a discussion... RenderAction This allows the view to call another controller, which will be responsible for interacting with the BLL and whatever data is necessary to its corresponding view. The calling view needs to be aware of the sub controller. This seems to provide a nice way to encapsulate partial views and controls, without having to modify the calling controller. RenderPartial The calling controller is still responsible for executing whatever code is associated with the partial view, and making sure that the model passed to the partial view contains the data it expects. Effectively, modifying the partial view potentially means modifying the calling controller. Annoying especially if this is used in multiple places. Portable Areas Place each control in its own project/area?

  Read the article

• On the search for my next great .Net Read

  - by user127954

  Just got done with "The art of unit testing". It was a great read and i think everyone should go buy a copy. With that said i think the next book I'm like to read would be a architecture / Design type book that would focus heavily on building your objects / software in such a way that it would be: Low Coupling High Cohesion Easily Maintainable / Extended Easy to test Easy to Navigate / Debug The above characteristcs are the most important ones but also maybe it would also include (but not necessary) designing for: Performance - Don't want to design a system at at the end find out its dog slow :) Scalability - Again don't want to design something at the end find out it won't scale. I'd also prefer (but not necessary again): Something newer - Architectural principles seem to gradually evolve / improve over time and id like something with current thinking. .Net as illustrating language - like i said above its not mandatory but since its what i use every day id prefer it to be in .net. Doesn't really matter if its in vb.net or c# Some of the topics that would be talked about its how to minimize dependencies and using interfaces throughout your solution rather than concrete classes. Maybe it would constract /compare some of the newest design principles like DDD, Repository Pattern, Ect... I already have "Clean Code" (don't know if its this type of book or not) and "Working effectively with legacy code" on my radar but id like to read a book based upon the topic i talked about above first. Is there such a book?

  Read the article

• More efficient R / Sweave / TeXShop work-flow?

  - by user594795

  I've now got everything to work properly on my Mac OS X 10.6 machine so that I can create decent looking LaTeX documents with Sweave that include snippets of R code, output, and LaTeX formatting together. Unfortunately, I feel like my work-flow is a bit clunky and inefficient: Using TextWrangler, I write LaTeX code and R code (surrounded by <<= above and @ below R code chunk) together in one .Rnw file. After saving changes, I call the .Rnw file from R using the Sweave command Sweave(file="/Users/mymachine/Documents/Assign4.Rnw", syntax="SweaveSyntaxNoweb") In response, R outputs the following message: You can now run LaTeX on 'Assign4.tex' So then I find the .tex file (Assign4.tex) in the R directory and copy it over to the folder in my documents ~/Documents/ where the .Rnw file is sitting (to keep everything in one place). Then I open the .tex file (e.g. Assign4.tex) in TeXShop and compile it there into pdf format. It is only at this point that I get to see any changes I have made to the document and see if it 'looks nice'. Is there a way that I can compile everything with one button click? Specifically it would be nice to either call Sweave / R directly from TextWrangler or TeXShop. I suspect it might be possible to code a script in Terminal to do it, but I have no experience with Terminal. Please let me know if there's any other things I can do to streamline or improve my work flow.

  Read the article

• Modules vs. Classes and their influence on descendants of ActiveRecord::Base

  - by Chris

  Here's a Ruby OO head scratcher for ya, brought about by this Rails scenario: class Product < ActiveRecord::Base has_many(:prices) # define private helper methods end module PrintProduct attr_accessor(:isbn) # override methods in ActiveRecord::Base end class Book < Product include PrintProduct end Product is the base class of all products. Books are kept in the products table via STI. The PrintProduct module brings some common behavior and state to descendants of Product. Book is used inside fields_for blocks in views. This works for me, but I found some odd behavior: After form submission, inside my controller, if I call a method on a book that is defined in PrintProduct, and that method calls a helper method defined in Product, which in turn calls the prices method defined by has_many, I'll get an error complaining that Book#prices is not found. Why is that? Book is a direct descendant of Product! More interesting is the following.. As I developed this hierarchy PrintProduct started to become more of an abstract ActiveRecord::Base, so I thought it prudent to redefine everything as such: class Product < ActiveRecord::Base end class PrintProduct < Product end class Book < PrintProduct end All method definitions, etc. are the same. In this case, however, my web form won't load because the attributes defined by attr_accessor (which are "virtual attributes" referenced by the form but not persisted in the DB) aren't found. I'll get an error saying that there is no method Book#isbn. Why is that?? I can't see a reason why the attr_accessor attributes are not found inside my form's fields_for block when PrintProduct is a class, but they are found when PrintProduct is a Module. Any insight would be appreciated. I'm dying to know why these errors are occurring!

  Read the article

• $_SESSION v. $_COOKIE

  - by taeja87

  I learned about $_SESSION about several weeks ago when creating a login page. I can successfully login and use it with variables. Currently I am trying to understand $_SESSION and $_COOKIE. Please correct me if I am wrong, I can use $_SESSION when logging in and moving around pages. With $_COOKIE, it is used to remember when I last visit and preferences. Another thing involving cookies is that when websites use advertisements (for example: Google AdSense), they use the cookies to track when visitor click on a advertisement, right? I can use both ($_SESSION & $_COOKIE)? I read somewhere that you can store the session_id as value for the cookie. Also, I read about security which let to me finding this: What do I need to store in the php session when user logged in?. Is using session_regenerate_id good for when a user comes back to the site? And this: How to store a cookie with php involving uniqid. For those wanting to know about the login, I use email and password. That way the user can be able to change their username. I look forward to learning more about these two from anybody who would like to share their knowledge about it. If I asked too many question, you can just answer the one that you have more experience with. If you need more information, just ask since I might have forgotten to include something. Thank You. Found this: What risks should I be aware of before allowing advertisements being placed on my website?

  Read the article

• c program pointer

  - by sandy101

  Hello , I am trying some programs in c face a problem with this program #include<stdio.h> int main() { int a=9,*x; float b=3.6,*y; char c='a',*z; printf("the value is %d\n",a); printf("the value is %f\n",b); printf("the value is %c\n",c); x=&a; y=&b; z=&c; printf("%u\n",a); printf("%u\n",b); printf("%u\n",c); x++; y++; z++; printf("%u\n",a); printf("%u\n",b); printf("%u\n",c); return 0; } can any one tell me what is the problem with this and i also want to know that when in the above case if the pointer value is incremented then will it over write the previous value address as suppose that the value we got in the above program (without the increment in the pointer value )is 65524 65520 65519 and after the increment the value of the pointer is 65526(as 2 increment for the int ) 65524(as 4 increment for the float ) 65520(as 1 increment for the char variable ) then if in that case will the new pointer address overwrite the content of the previous address and what value be contained at the new address ......plz help

  Read the article

• Is it possible to install into Program Files with limited privileges?

  - by Marek

  I have an application that will be deployed as MSI package (authored in WiX). I am deciding whether to specify elevated or limited privileges as required for the installer. The application does not include anything requiring elevated privileges besides the default install location, which is under Program Files. Now the problem: If I specify elevated privileges, then the user is prompted by UAC for administrator password during the installation. This is not required and prevents non-admin users from installing. If I specify limited privileges, then the user is presented with a dialog to select install location with Program Files being default. In case they do not change the install location (95 % of end users probably won't), then the installer will fail with a message that they should contact the Administrator or run the application as administrator. If they launch the installer as Administrator then they can install into Program Files without problem - but most of the users won't probably know how to launch an installer as administrator. I can potentially set the default install location to e.g. C:\Company name\Program\, but this seems nonstandard to me and majority of users will not probably like this (they are probably used to installing into Program Files). How do you solve this problem with installing applications under limited user accounts?

  Read the article

• C++ Loop - Need variable to accumulate sum

  - by user1780064

  I'm writing a program to ask the user to enter a value between 5 and 21 (inclusive). If the number entered is not in this range, it prints, "Please try again". If the number is within the range, I need to take that number, and print the sum of all the numbers from 1 to the value entered. So if the user entered "7", the sum would be "28". I successfully wrote the first loop, in the case of the number not being within the range, but cannot figure out how to run the second loop- whether to use a while, do-while, or for loop. Please advise. #include <iostream> int main () { int uservalue; int count; int sum; //Prompt user for input do { cout << "Enter a value from 5 to 21: "; cin >> uservalue; if (uservalue < 5 || uservalue > 21) cout << "Value out of range. Try again..." << endl; } while (uservalue < 5 || uservalue > 21); cout << endl; //Loop to accumulate sum for (count = 1, count < uservalue, count++;) { sum = uservalue + count; if (uservalue <= 5 || uservalue <= 21) cout << the sum is " << sum << endl; } return 0; }

  Read the article

• JAR files, don't they just bloat and slow Java down?

  - by Josamoto

  Okay, the question might seem dumb, but I'm asking it anyways. After struggling for hours to get a Spring + BlazeDS project up and running, I discovered that I was having problems with my project as a result of not including the right dependencies for Spring etc. There were .jars missing from my WEB-INF/lib folder, yes, silly me. After a while, I managed to get all the .jar files where they belong, and it comes at a whopping 12.5MB at that, and there's more than 30 of them! Which concerns me, but it probably and hopefully shouldn't be concerned. How does Java operate in terms of these JAR files, they do take up quite a bit of hard drive space, taking into account that it's compressed and compiled source code. So that can really quickly populate a lot of RAM and in an instant. My questions are: Does Java load an entire .jar file into memory when say for instance a class in that .jar is instantiated? What about stuff that's in the .jar that never gets used. Do .jars get cached somehow, for optimized application performance? When a single .jar is loaded, I understand that the thing sits in memory and is available across multiple HTTP requests (i.e. for the lifetime of the server instance running), unlike PHP where objects are created on the fly with each request, is this assumption correct? When using Spring, I'm thinking, I had to include all those fiddly .jars, wouldn't I just be better off just using native Java, with say at least and ORM solution like Hibernate? So far, Spring just took extra time configuring, extra hard drive space, extra memory, cpu consumption, so I'm concerned that the framework is going to cost too much application performance just to get for example, IoC implemented with my BlazeDS server. There still has to come ORM, a unit testing framework and bits and pieces here and there. It's just so easy to bloat up a project quickly and irresponsibly easily. Where do I draw the line?

  Read the article

< Previous Page | 459 460 461 462 463 464 465 466 467 468 469 470  | Next Page >