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  • This code appears to achieve the return of a null reference in C++

    - by Chuck
    Hi folks, My C++ knowledge is somewhat piecemeal. I was reworking some code at work. I changed a function to return a reference to a type. Inside, I look up an object based on an identifier passed in, then return a reference to the object if found. Of course I ran into the issue of what to return if I don't find the object, and in looking around the web, many people claim that returning a "null reference" in C++ is impossible. Based on this advice, I tried the trick of returning a success/fail boolean, and making the object reference an out parameter. However, I ran into the roadblock of needing to initialize the references I would pass as actual parameters, and of course there is no way to do this. I retreated to the usual approach of just returning a pointer. I asked a colleague about it. He uses the following trick quite often, which is accepted by both a recent version of the Sun compiler and by gcc: MyType& someFunc(int id) { // successful case here: // ... // fail case: return *static_cast<MyType*>(0); } // Use: ... MyType& mt = somefunc(myIdNum); if (&mt) // test for "null reference" { // whatever } ... I have been maintaining this code base for a while, but I find that I don't have as much time to look up the small details about the language as I would like. I've been digging through my reference book but the answer to this one eludes me. Now, I had a C++ course a few years ago, and therein we emphasized that in C++ everything is types, so I try to keep that in mind when thinking things through. Deconstructing the expression: "*static_cast(0);", it indeed seems to me that we take a literal zero, cast it to a pointer to MyType (which makes it a null pointer), and then apply the dereferencing operator in the context of assigning to a reference type (the return type), which should give me a reference to the same object pointed to by the pointer. This sure looks like returning a null reference to me. Any advice in explaining why this works (or why it shouldn't) would be greatly appreciated. Thanks, Chuck

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  • Is there anyway to get pdb and Mac Terminal to play nicely?

    - by Ross
    When debugging my django apps I use pdb for interactive debugging with pdb.set_trace(). However, when I amend a file the local django webserver restarts and then I cant see what I type in the terminal, until I type reset. Is there anyway for this to happen automatically? It can be real annoying, having to cancel the runserver and reset and restart it all the time. I'm told it doesn't happen on other OS's (ubuntu) so is there anyway to make it not happen on the Mac? (I'm using Snow Leopard).

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  • Comparison in Monit Permissions Testing

    - by beanland
    I'm trying to use Monit to check the permissions of a particular directory, but I only care that it's readable to all users. I don't care about any other permissions (write, execute) for the owner, group, or all. I also don't care about any special permissions. Knowing that I can't change the permissions of this directory, and with the possibility of another administrator changing these permissions without affecting my processes that rely on this directory (i.e., granting or revoking write access to the group), is it possible to check for a minimum permission in Monit? I have this which is currently working: check directory archive path /var/home/archive/ if failed perm 0755 then alert But I would like to have something like tihs: check directory archive path /var/home/archive/ if failed perm > 444 then alert This is failing for me. Is it possible to use comparison operators in Monit's permissions checking? If not, are there any workarounds?

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  • Reflection for Class of generic parameter in Java?

    - by hatboysam
    Imagine the following scenario: class MyClass extends OtherClass<String>{ String myName; //Whatever } class OtherClass<T> { T myfield; } And I am analyzing MyClass using reflection specifically (MyClass.class).getDeclaredFields(), in this case I will get the following fields (and Types, using getType() of the Field): myName --> String myField --> T I want to get the actual Type for T, which is known at runtime due to the explicit "String" in the extends notation, how do I go about getting the non-genetic type of myField?

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  • problem in displays data in one page

    - by user318068
    hi ,,,,, I have a problem in the following code ... The following code works as follows displays the invites for each member so that if he had five invite from supposed to be displayed all on one page But before you code that does not function Proper image is the only display one invite on the page and until the approval or rejection of the invitation displays the invite the other .... But this is not my want to offer all on one page I wish I could solve the problem and I can view all calls in one page I think that the problem is in the order code I think that the problem is in the order code my code : <?php session_start(); if (!isset($_SESSION['user_id'])) { header("Location: login.php"); } $id=$_SESSION['user_id']; ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Untitled Document</title> </head> <body> <center> <?php include("connect.php"); $sql =mysql_query("select * from ninvite where recieverMemberID ='$id' and viwed= '0'"); $num =mysql_num_rows($sql); echo $num ; if ($num>0) { while($row=mysql_fetch_array($sql)) { $sender=$row['SenderMemberID']; $room=$row['RoomID']; $sql =mysql_query("select MemberName from members where MemberID ='$sender' "); $sql1 =mysql_query("select RoomName from rooms where RoomID ='$room' "); while($row=mysql_fetch_array($sql)) {$mem =$row['MemberName']; } while($rows=mysql_fetch_array($sql1)) { $Ro =$rows['RoomName']; ?> <form action="join.php" method="post"> <label> </label> <br/> <label> <?php echo " you have invite from $mem to join $Ro"; ?> </label> <br/><br/> <label>accept</label> <input name="radio1" type="radio" value="accpet" /> <label>reject</label> <input name="radio1" type="radio" value="Reject" /><br/> <input type="submit" name="submit" value="done" /> </form> <?php } } } ?> </center> </body> </html> thanks alot. my SQl -- phpMyAdmin SQL Dump -- version 3.2.4 -- http://www.phpmyadmin.net -- Host: localhost -- Generation Time: May 07, 2010 at 12:50 ? -- Server version: 5.1.41 -- PHP Version: 5.3.1 SET SQL_MODE="NO_AUTO_VALUE_ON_ZERO"; /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT /; /!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS /; /!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION /; /!40101 SET NAMES utf8 */; -- -- Database: tr -- -- Table structure for table joinroom CREATE TABLE IF NOT EXISTS joinroom ( MemberID int(10) NOT NULL, RoomID int(10) NOT NULL, PRIMARY KEY (MemberID,RoomID) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; -- -- Dumping data for table joinroom INSERT INTO joinroom (MemberID, RoomID) VALUES (28, 1); -- -- Table structure for table members CREATE TABLE IF NOT EXISTS members ( MemberID int(10) unsigned NOT NULL AUTO_INCREMENT, MemberName varchar(20) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberPass varchar(10) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberEmail varchar(30) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberLocation text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, MemberImg text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, PRIMARY KEY (MemberID) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=34 ; -- -- Dumping data for table members INSERT INTO members (MemberID, MemberName, MemberPass, MemberEmail, MemberLocation, MemberImg) VALUES (28, 'marwa', '1234', '[email protected]', 'mmmmmm', 'dddddddddd'), (29, 'nora', '1234', '[email protected]', 'fffffffffffgg', 'gggggggggggggg'), (30, 'soso', '1234', '[email protected]', 'ffffffff', 'kkkkkkkkkkkkkkkkkk'), (31, 'gege', '1234', '[email protected]', 'kkkkkkkkkkkkkkkk', 'uuuuuuuuuuuuuuuuu'), (32, 'nono', '1234', '[email protected]', 'ggggggggggggaaaaa', 'aaaaaaaaaaaaaaa'), (33, 'nda', '1234', '[email protected]', 'kkkkkkkkkkkkkkkk', 'ooooooooooooooo'); -- -- Table structure for table ninvite CREATE TABLE IF NOT EXISTS ninvite ( SenderMemberID int(11) NOT NULL AUTO_INCREMENT, recieverMemberID varchar(30) NOT NULL, RoomID int(11) NOT NULL, viwed int(11) NOT NULL, PRIMARY KEY (SenderMemberID,recieverMemberID,RoomID) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=33 ; -- -- Dumping data for table ninvite INSERT INTO ninvite (SenderMemberID, recieverMemberID, RoomID, viwed) VALUES (28, '33', 1, 0), (28, '32', 1, 0), (28, '31', 1, 0); /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT /; /!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS /; /!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

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  • How do you optimize database performance when providing results for autocomplete/iterative search?

    - by Howiecamp
    Note: In this question I'm using the term "autocomplete" (or "iterative search") to refer to returning search-as-you-type results, e.g. like Google Search gives you. Also my question is not specific to web applications vs. fat client apps. How are SQL SELECT queries normally constructed to provide decent performance for this type of query, especially over arbitrarily large data sets? In the case where the search will only query based on the first n characters (easiest case) am I still issuing a new SELECT result FROM sometable WHERE entry LIKE... on each keypress. Even with various forms of caching this seems like it might result in poor performance. In cases where you want your search string to return results with prefix matches, substring matches, etc. it's an even more difficult problem. Looking at a case of searching a list of contacts, you might return results that match FirstName + LastName, LastName + FirstName, or any other substring.

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  • How do you manage web navigation info in your application?

    - by Dave
    I’m building an application where different users will have different menu items available to them depending on what they’ve paid for. There will also be multiple levels to the menu hierarchy. What’s the best approach to this problem? I’m assuming I need a database table that represents the menu hierarchy, including the parent-child relationships of the nodes in the navigation as well as the sorting of the items. Then another table which I use to manage whether a user is authorized to access a particular item in that table. When I render the view, I’d reference the menus, and the access rights of the user to output the menu, and I’d also need a function to check that same authorization from each controller in case a user manually types in a URL of a controller they’re not supposed to have access to. Is this the right approach? Any suggestions for caching this to prevent the constant look-ups of this type of info? I’m open to any suggestions on how you may have approached this type of requirement.

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  • Using Google Map Headers (YM4R) on Heroku

    - by Kevin
    I have the following at the top of my view: <%= GMap.header %> Heroku is giving me an ActionView::TemplateError on that line.... this works on my own machine but not on Heroku.... why is that? Is there something about Heroku that doesn't allow? In the final compile on the browser, the above code translates into this on the client side: <script src="http://maps.google.com/maps?file=api&amp;v=2.x&amp;key=XXXXX;hl=&amp;sensor=false" type="text/javascript"> </script> <script src="/javascripts/ym4r-gm.js" type="text/javascript"></script>

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  • Connection and Collection Interfaces in Java

    - by Bhupi
    Which class implements all the Connection Interfaces which are in javax.microedition.io package and how? And in the same way which class implements the some of Collection interfaces like Iterator interface. I saw a code: - Iterator it; ArrayList list = new ArrayList(); it = list.iterator(); The iterator() return type is "Iterator" which is an interface. Please tell me what this code is doing is it returning an object of type Iterator? but as far as I know, interface can't be initialized.

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  • Is there a design pattern for this ?

    - by ytrewq
    I have a component that needs to call a specific service depending on the input it receives. So my component has to look at the input and based on a configuration that says "for this input call this service with this data" needs to call the proper service. The services have a common signature method and a specific one (each). I thought about an abstract class that includes the signatures for all three methods. The implementation for the two services will override all three methods (throwing NotImplementedException for the methods that are not supported by current service). A component that could be initialized with a map (that for each input type will have the type of the service to be called) will also be defined. Do you have a better approach to cope this scenario ?

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  • How to specify which GCC for MacPorts to use?

    - by penyuan
    I compiled GCC 4.4.3 and installed it in /usr/local/bin, but whenever I install a port via MacPorts 1.8.2 the verbose output says MacPorts is using /usr/bin/gcc-4.2: checking for gcc... /usr/bin/gcc-4.2 How do I make MacPorts find my own GCC 4.4.3? Here is my existing path: /opt/local/bin:/opt/local/sbin:/usr/local/bin:/usr/local/lib:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin Thank you! P.S. I am running Mac OS X 10.6.2 Snow Leopard.

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  • What jQuery is triggered when a user selects a "drop down list" option

    - by Ankur
    I want to display a different form for different selections of this drop down list: <label> <select name="type" id="type"> <option value="object" selected="selected">Object</option> <option value="number">Number</option> <option value="text">Text</option> <option value="date">Date</option> <option value="time">Time</option> <option value="geo">Geospatial</option> <option value="currency">Currency</option> </select> </label> What would be the jQuery event that is triggered when a user selects one of these options. Would the .click() event be triggered in this case as well?

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  • How to make IE and Firefox display hidden elements the same (IE shifts visible element)

    - by Dale
    Rendering the same html in IE and Firefox gives me a different result because in IE, the hidden checkbox is not ignored, from a layout perspective: <html><head> <style type="text/css"> <!-- #checkboxhide { position: relative; visibility: hidden; font-size: 8.5pt; font-weight: font-family: verdana;} //--> </style> </head><body> <table><tr> <td>|</td> <td><span id="checkboxhide"><input type="checkbox" hidden="" name="blah"></span>|Greetings Earthings</td> </tr></table> </body></html> How can I get the two (or more) browsers to show the same thing?

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  • background picture for textview

    - by AndyAndroid
    Hi, I have a textview and a nine-patch image. Assigning this image in the xml editor to the tag "background" works as desired. Now I want to set this image dynamically in the coding, I thought myTextView.setBackgroundDrawable(mydrawable); would be the right thing to do. My png is in res/drawable. The API says that mydrawable needs to be an object of type drawable R.drawable.myninepatch is of type int. So my problem is that I have to convert from that int to a drawable somehow. Then I thought I can use a constructor NinePatchDrawable mydrawable = new NinePatchDrawable(); But I am again not able to construct such an object. Anyone an idea? Thanks.

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  • updated validation example for web api

    - by MonkeyBonkey
    I tried the validation example code for web api on the latest mvc 4 download and I'm getting some errors. Does anyone have an updated example of the ValidationActionFilter class. Here's the original code public class ValidationActionFilter : ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext context) { var modelState = context.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } context.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } I'm getting an error on HttpResponseMessage The non-generic type 'System.Net.Http.HttpResponseMessage' cannot be used with type arguments Also it looks like I need to add a Json reference, but should I be using JSON.net instead? An example of this using Json.net?

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  • Workgroup connection: You may not have permission

    - by Afiefh
    I have two Windows XP computers connected through an Ad-Hoc network, computer A creates the network and B connects to it. Both computers are on the Mshome network and have file and printer sharing enabled, and they can ping one another through the adhoc network. The result is that computer A can see computer B, but B cannot see A in the workgroup. But when A tries to access B I get a "you might not have permission to access" error telling me to contact the administrator. I tries to google the error, but most posts talk about problems connecting different versions of Windows to each other. I tried turning off the firewalls on both machines and checking if the required services are running. Nothing helped. Please excuse my ignorance on Windows networking, I haven't used Windows in around 10 years.

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  • SQL Server 2008 Stored Procedure

    - by user238319
    I cannot store the date data type variables using stored procedure. My code is: ALTER PROCEDURE [dbo].[Access1Register] -- Add the parameters for the stored procedure here @MobileNumber int, @CitizenName varchar(50), @Dob char(8), @VerificationCode int AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- Insert statements for procedure here select CAST(@dob As DATE) Insert Into Access1 (MobileNo,CitizenName,Dob,VerificationCode) values(@MobileNumber,@CitizenName,@Dob,@VerificationCode) go If I exec this procedure it is executing, but there is an error occured in the date type variable. It's raising the error as invalid item '-'.

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  • Dynamic Custom Fields for Data Model

    - by Jerry Deng
    I am in the process of creating a dynamic database where user will be able to create resource type where he/she can add custom fields (multiple texts, strings, and files) Each resource type will have the ability to display, import, export its data; I've been thinking about it and here are my approaches. I would love to hear what do you guys think. Ideas: just hashing all the custom data in a data field (pro: writing is easier, con: reading back out may be harder); children fields (the model will have multiple fields of strings, fields of text, and fields for file path); fixed number of custom fields in the same table with a key mapping data hash stored in the same row; Non-SQL approach, but then the problem would be generating/changing models on the fly to work with different custom fields;

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  • SOW, SLA, TOS....am i missing anything else ?

    - by fwfwfw
    when doing long term sale of service or software, what type of legal contracts need to be drafted ? i'm not a lawyer, and was looking for a general template on statement of work, service level agreements and terms of services. how are java enterprise applications requiring server side logic, delivered by the vendor to the client ? do they deliver the actual hardware server with everything installed ? java apps can be decompiled and source code exposed, what type of legal paper would you need to draft to protect your asset and Intellectual property ?

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  • MVVM Light DialogMessage

    - by Cha0sEngine
    hi, im trying to use the mvvmlight DialogMessage. var message = new DialogMessage( "Confirm Delete", RemoveAddressAction) { Button = MessageBoxButton.OKCancel, Caption = "Caption??" }; VS2010 undelines the "Button = MessageBoxButton.OKCancel" line complaining about "Cannot convert source type 'System.Windows.MessageBoxButton [PresentationFramework, Version=3.0.0.0, Culture...] to target type 'System.Windows.MessageBoxItem [GalaSoft.MvvmLight, Version=3.0.0.29216, ...] And a similar issue on the code behind on the view when I try to use the DialogMessage to show the messagebox. Has anyone encountered this before? I have no clue how to fix it. Thanks.

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  • How to print a specific value in array in PHP?

    - by cateye
    array(2) { [0]=> object(stdClass)#144 (7) { ["id"]=> string(1) "2" ["name"]=> string(8) "name1" ["value"]=> string(22) "Lorem Ipsum Dolar Amet" ["type"]=> string(8) "textarea" ["group"]=> string(1) "1" ["published"]=> string(1) "1" ["ordering"]=> string(1) "1" } [1]=> object(stdClass)#145 (7) { ["id"]=> string(1) "4" ["name"]=> string(6) "Link1" ["value"]=> string(36) "abcabcab" ["type"]=> string(4) "link" ["group"]=> string(1) "1" ["published"]=> string(1) "1" ["ordering"]=> string(1) "2" } } I want to print only "value" (abcabcab) of id=4. How can I achieve this?

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  • jQuery.Form wont submit

    - by kim
    Im´trying to submit a form without refreshing the page, but I´m having a problem. When I click submit the page refreshes and anothing gets posted. Here is the code, what am I doing wrong? (I´m a newbie) jQuery 1.4.2 and the jQuery Form Plugin 2.43 is present. tnx $(document).ready(function() { var options = { target: '#output2', url: https://graph.facebook.com/<%=fbUid%>/feed, type: post, clearForm: true // clear all form fields after successful submit //dataType: null // 'xml', 'script', or 'json' (expected server response type) //resetForm: true // reset the form after successful submit // $.ajax options can be used here too, for example: //timeout: 3000 }; // bind to the form's submit event $('#fbPostStatus').submit(function() { // inside event callbacks 'this' is the DOM element so we first // wrap it in a jQuery object and then invoke ajaxSubmit $(this).ajaxSubmit(options); // !!! Important !!! // always return false to prevent standard browser submit and page navigation return false; }); });

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  • Numpy/Python performing terribly vs. Matlab

    - by Nissl
    Novice programmer here. I'm writing a program that analyzes the relative spatial locations of points (cells). The program gets boundaries and cell type off an array with the x coordinate in column 1, y coordinate in column 2, and cell type in column 3. It then checks each cell for cell type and appropriate distance from the bounds. If it passes, it then calculates its distance from each other cell in the array and if the distance is within a specified analysis range it adds it to an output array at that distance. My cell marking program is in wxpython so I was hoping to develop this program in python as well and eventually stick it into the GUI. Unfortunately right now python takes ~20 seconds to run the core loop on my machine while MATLAB can do ~15 loops/second. Since I'm planning on doing 1000 loops (with a randomized comparison condition) on ~30 cases times several exploratory analysis types this is not a trivial difference. I tried running a profiler and array calls are 1/4 of the time, almost all of the rest is unspecified loop time. Here is the python code for the main loop: for basecell in range (0, cellnumber-1): if firstcelltype == np.array((cellrecord[basecell,2])): xloc=np.array((cellrecord[basecell,0])) yloc=np.array((cellrecord[basecell,1])) xedgedist=(xbound-xloc) yedgedist=(ybound-yloc) if xloc>excludedist and xedgedist>excludedist and yloc>excludedist and yedgedist>excludedist: for comparecell in range (0, cellnumber-1): if secondcelltype==np.array((cellrecord[comparecell,2])): xcomploc=np.array((cellrecord[comparecell,0])) ycomploc=np.array((cellrecord[comparecell,1])) dist=math.sqrt((xcomploc-xloc)**2+(ycomploc-yloc)**2) dist=round(dist) if dist>=1 and dist<=analysisdist: arraytarget=round(dist*analysisdist/intervalnumber) addone=np.array((spatialraw[arraytarget-1])) addone=addone+1 targetcell=arraytarget-1 np.put(spatialraw,[targetcell,targetcell],addone) Here is the matlab code for the main loop: for basecell = 1:cellnumber; if firstcelltype==cellrecord(basecell,3); xloc=cellrecord(basecell,1); yloc=cellrecord(basecell,2); xedgedist=(xbound-xloc); yedgedist=(ybound-yloc); if (xloc>excludedist) && (yloc>excludedist) && (xedgedist>excludedist) && (yedgedist>excludedist); for comparecell = 1:cellnumber; if secondcelltype==cellrecord(comparecell,3); xcomploc=cellrecord(comparecell,1); ycomploc=cellrecord(comparecell,2); dist=sqrt((xcomploc-xloc)^2+(ycomploc-yloc)^2); if (dist>=1) && (dist<=100.4999); arraytarget=round(dist*analysisdist/intervalnumber); spatialsum(1,arraytarget)=spatialsum(1,arraytarget)+1; end end end end end end Thanks!

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  • Different versions in manifest on different machines

    - by Terry777
    Hi guys, Have two machines, both with VS2005 SP1 installed and with the WinSXS showing the same things installed. When one machine builds a particular C++ .dll .vcproj it ends up with <assemblyIdentity type='win32' name='Microsoft.VC80.MFC' version='8.0.50727.762' processorArchitecture='x86' publicKeyToken='1fc8b3b9a1e18e3b' /> in its manifest file. But on the other machine it ends up with <assemblyIdentity type='win32' name='Microsoft.VC80.MFC' version='8.0.50608.0 processorArchitecture='x86' publicKeyToken='1fc8b3b9a1e18e3b' /> even though this machine does not have '8.0.50608.0' libraries listed in its WinSXS. The .dll built on this machine with the older version referenced has some problems. I have ensured both machines have the same latest source code and references etc.. What could be causing it to build with the different reference? Thanks! Terry

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