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C# and ASP.NET MVC: Using #if directive in a view

- by Mega Matt

Hi all, I've got a conditional compilation symbol I'm using called "RELEASE", that I indicated in my project's properties in Visual Studio. I want some particular CSS to be applied to elements when the RELEASE symbol is defined, and I was trying to do that from the view, but it doesn't seem to be working. My view code looks like this (shortened a bit for demo purposes): <% #if (RELEASE) %> <div class="releaseBanner">Banner text here</div> <% #else %> <div class="debugBanner">Banner text here</div> <% #endif %> With this code, and with the RELEASE symbol set, the 'else' code is running and I'm getting a div with the debugBanner class. So it doesn't seem to think that RELEASE is defined. It's worth noting that my actual C# code in .cs files is recognizing RELEASE and runs the correct code. It's only the view that is giving me the problem. Does anyone have any insight into this? Any help would be appreciated. Thanks.

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WINDOWS: Your computer hangs. You can windows + R (run dialog) but performance is so halted taskMGR

- by John Sullivan

The question is, what process are available to try to recover from total system instability before pulling the plug when we can do nothing but programs or batches in the path from the run dialog (windows + r key), and performance is so dead that taskMGR / procEXP / other programs with visual guis are not usable? I am not a windows expert, but ideally someone out there has written a program that does more or less stuff like this: Immediately set (or perhaps I can set from the run prompt) its priority to extremely high, evaluate performance bottlenecks. E.g. is CPU 100%? If so identify offending program(s) or problems. Attempt / log fixes, then provide crude feedback asking the user if his performance has stabilized enough to abort, wait a few seconds, if no feedback continue, etc. etc. Eventually try to do any "system cleanup" if the program decides it cannot recover and perhaps finally provide a series of beeps to the user, or what have you, to say "OK, I give up, time to pull the plug". Ideally create a log, when able. These kinds of horrible hangs are a situation where surely trying something, anything, is better than nothing -- as long as that something is intelligent -- when the alternative is ripping out the power coord. Again, I am not a windows expert, so perhaps there is a much more elegant "hands on" approach I am not aware of.

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Tools for debugging when debugger can't get you there?

- by brian1001

I have a fairly complex (approx 200,000 lines of C++ code) application that has decided to crash, although it crashes a little differently on a couple of different systems. The trick is that it doesn't crash or trap out in debugger. It only crashes when the application .EXE is run independently (either the debug EXE or the release EXE - both behave the same way). When it crashes in the debug EXE, and I get it to start debugging, the call stack is buried down into the windows/MFC part of things, and isn't reflecting any of my code. Perhaps I'm seeing a stack corruption of some sort, but I'm just not sure at the moment. My question is more general - it's about tools and techniques. I'm an old programmer (C and assembly language days), and a relative newcomer (couple/few years) to C++ and Visual Studio (2003 for this projecT). Are there tricks or techniques anyone's had success with in tracking down crashing issues when you cannot make the software crash in a debugger session? Stuff like permission issues, for example? The only thing I've thought of is to start plugging in debug/status messages to a logfile, but that's a long, hard way to go. Been there, done that. Any better suggestions? Am I missing some tools that would help? Is VS 2008 better for this kind of thing? Thanks for any guidance. Some very smart people here (you know who you are!). cheers.

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How to import properties of an external API into Script#

- by AndrewDotHay

I'm using Script# inside Visual Studio 2010 to import the API for the HTML5 Canvas element. Its working great for things like FillRect(), MoveTo(), LineTo() and so on. I've declared the following interface and then I can code against it in C#. Then, Script# converts it to JavaScript nicely. public interface CanvasContext { void FillRect(int x, int y, int width, int height); void BeginPath(); void MoveTo(int x, int y); void LineTo(int x, int y); void Stroke(); void FillText(string text, int x, int y); } I want to include the StrokeStyle property that takes a simple string. The following interface definition produces a prefix in the JavaScript, which causes it to fail. string StrokeStyle { get; set; } string Font { get; set; } The previous property will create this JavaScript: ctx.set_strokeStyle('#FF0'); How can I get Script# to generate the simple assignment properties of the canvas context without the get_/set_ prefix?

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Slow loading of UITableView. How know why?

- by mamcx

I have a UITableView that show a long list of data. Use sections and follow the sugestion of http://stackoverflow.com/questions/695814/how-solve-slow-scrolling-in-uitableview . The flow is load a main UITableView & push a second selecting a row from there. However, with 3000 items take 11 seconds to show. I suspect first from the load of the records from sqlite (I preload the first 200). So I cut it to only 50. However, no matter if I preload only 1 or 500, the time is the same. The view is made from IB and all is opaque. I run out of ideas in how detect the problem. I run the Instruments tool but not know what to look. Also, when the user select a cell from the previous UITable, no visual feedback is show (ie: the cell not turn selected) for a while so he thinks he not select it and try several times. Is related to this problem. What to do? NOTE: The problem is only in the actual device: iPod Touch 2d generation Using fmdb as sqlite api Doing the caching in viewDidLoad Using NSDictionary for the caching Using a NSAutoreleasePool for the caching part. Only caching the row ID & mac 4 fields necesary to show the cell data UIView made with interface builder, SDK 2.2.1 Instruments say I use 2.5 MB in the device

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Overhead of calling tiny functions from a tight inner loop? [C++]

- by John

Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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Developers: How does BitLocker affect performance?

- by Chris

I'm an ASP.NET / C# developer. I use VS2010 all the time. I am thinking of enabling BitLocker on my laptop to protect the contents, but I am concerned about performance degradation. Developers who use IDEs like Visual Studio are working on lots and lots of files at once. More than the usual office worker, I would think. So I was curious if there are other developers out there who develop with BitLocker enabled. How has the performance been? Is it noticeable? If so, is it bad? My laptop is a 2.53GHz Core 2 Duo with 4GB RAM and an Intel X25-M G2 SSD. It's pretty snappy but I want it to stay that way. If I hear some bad stories about BitLocker, I'll keep doing what I am doing now, which is keeping stuff RAR'ed with a password when I am not actively working on it, and then SDeleting it when I am done (but it's such a pain).

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IIS publish of WCF service -- fails with no error message

- by tavistmorph

I havea WCF service which I publish from Visual Studio 2008 to an IIS 6. According to the output window of VS, the publish succeeded, no error messages or warnings. When I look at IIS, the virtual directory was created, but there is no .svc listed in the directory. The directory just has my web.config and a bin. Any attempts to call my WCF service fail cause they don't exist. How can I see an error message of what's going wrong? By trial-and-error, I discovered changing my app.config before publishing will make the service show up. Namely my app.config file has these lines: <binding ...> <security mode="Transport"> <transport clientCreditionalType="None"/> </security> </binding> If I switch "Transport" to "None", then my service shows up on IIS. But I do have a certificate installed on IIS on the server, and as far as I can tell, everything is configured correctly on the server. There is no error message in the event log. How can I get a find more error messages about why the service is failing to show up?

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Execute files included in Resource folder

- by Sumeet Pujari

In WPF application where I have included some files in resources, I want to execute them on a button click. How do I specify a path in Process.Start(). private void button1_Click_2(object sender, RoutedEventArgs e) { Process.Start("test.txt"); } Or is there any other way? private void button1_Click_2(object sender, RoutedEventArgs e) { string path = System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) + @"\test.txt"; if (File.Exists(path)) { Process.Start(new ProcessStartInfo(path)); } else { MessageBox.Show("No file found"+path); } I added a message box and it showed No files found. :( EDIT: I Tried to check the path after publishing and this what i got. No File Found With a Path - C:\Users\Administrator\AppData\Local\Apps\2.0... test.txt Before I published the Application I got a path which id No File Found at ..project..\bin\Debug\test.txt which is obvious since my Resource file not included there its Under a Resource Folder and not Debug when i add a test file in debug it open without any problem. Can someone Help throwing some light on this case. EDIT: I want to open a file from Resource directory @ C:\Users\Administrator\Documents\Visual Studio 2010\Projects\FastFix\FastFix\Resources Which would be included in my project when i am going to publish it is going to run as a standalone application without installation.

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Java Socket - how to catch Exception of BufferedReader.readline()

- by Hasan Tahsin

I have a Thread (let's say T1) which reads data from socket: public void run() { while (running) { try { BufferedReader reader = new BufferedReader( new InputStreamReader(socket.getInputStream()) ); String input = reader.readLine(); } catch (IOException e) { e.printStackTrace(); } } } Another Thread (lets say T2) try to finish the program in one of its method. Therefore T2 does the following: T1.running = false; socket.close(); Here is this scenario for which i couldn't find a solution: T1 is active and waiting for some input to read i.e. blocking. context switching T2 is active and sets running to false, closes the socket context switching because T1 was blocking and T2 closed the socket, T1 throws an Exception. What i want is to catch this SocketException. i can't put a try/catch(SocketException) in T1.run(). So how can i catch it in T1's running-method? If it's not possible to catch it in T1's running, then how can i catch it elsewhere? PS: "Another question about the Thread Debugging" Normally when i debug the code step by step, i lose the 'active running line' on a context switch. Let's say i'm in line 20 of T1, context switch happens, let's assume the program continues from the 30.line of T2, but the debugger does not go/show to the 30.line of T2, instead the 'active running line' vanishes. So i lose the control over the code. I use Eclipse for Java and Visual Studio for C#. So what is the best way to track the code while debugging on a context switch ?

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C# form - checkboxes do not respond to plus/minus keys - easy workaround?

- by Scott

On forms created with pre dotNET VB and C++ (MFC), a checkbox control responded to the plus/minus key without custom programming. When focus was on the checbox control, pressing PLUS would check the box, no matter what the previous state (checked/unchecked), while pressing MINUS would uncheck it, no matter the previous state. C# winform checkboxes do not seem to exhibit this behavior. Said behavior was very, very handy for automation, whereby the automating program would set focus to a checkbox control and issue a PLUS or MINUS to check or uncheck it. Without this capability, that cannot be done, as the automation program (at least the one I am using) is unable to query the current state of the checkbox (so it can decide whether to issue a SPACE key to toggle the state to the desired one). I've gone over the properties of a checkbox in the Visual Studio 2008 IDE and could not find anything that would restore/enable response to PLUS/MINUS. Since I am in control of the sourcecode for the WinForms in question, I could replace all checkbox controls with a custom checkbox control, but blech, I'd like to avoid that - heck, I don't think I could even consider that given the amount of refactoring that would need to be done. So the bottom line is: does anyone know of a way to get this behavior back more easily than a coding change?

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Serial Data Not Transmitted in C# Application

- by Jim Fell

Hello. I have a C# application wherein serial (COM1) data appears to sometimes not get transmitted. Following is a simplified snippet of my code (calls to textBox writes have been removed): try { serialPort1.Write("D"); serialPort1.Write(msg, 0, 512); serialPort1.Write("d"); serialPort1.Write(pCsum, 0, 2); } catch (SystemException ex) { /* ... */ } What is odd is that this same code works just fine when the port is configured for 115.2Kbps. However, when running at 9600bps data that should be transmitted by this code seems to not get transmitted. I have verified this by monitoring the receive flag on the remote device. No exceptions are thrown from within the try statement. Is there something else (Flush, etc.) that I should be doing to make sure the data is transmitted? Any thoughts or suggestions you may have would be appreciated. I'm using Microsoft Visual C# 2008 Express Edition. Thanks.

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What is the best way to embed SQL in VB.NET.

- by Amy P

I am looking for information on the best practices or project layout for software that uses SQL embedded inside VB.NET or C#. The software will connect to a full SQL DB. The software was written in VB6 and ported to VB.NET, we want to update it to use .NET functionality but I am not sure where to start with my research. We are using Visual Studio 2005. All database manipulations are done from VB. Update: To clarify. We are currently using SqlConnection, SqlDataAdapter, SqlDataReader to connect to the database. What I mean by embed is that the SQL stored procedures are scripted inside our VB code and then run on the db. All of our tables, stored procs, views, etc are all manipulated in the VB code. The layout of our code is quite messy. I am looking for a better architecture or pattern that we can use to organize our code. Can you recommend any books, webpages, topics that I can google, etc to help me better understand the best way for us to do this.

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VB.NET Program Locks Up with Internet Explorer Opened

- by aaronsj

I'm using Visual Studio 2008 and developing a VB.NET application. I'm having strange lockup problems with my program, but only when Internet explorer 8 is opened. When I cover my form with another window and then uncover it, I find that it has locked up. My program has no references to IE and the only thing it even has to do with IE is using Process.Start with a web address. My program works fine and exactly as it should, but only when IE is not opened. Does anyone know why a program would lock up only while IE is running? Edit: I've done some digging and I've found the offending thread in my program. I don't know what starts this thread or what it does, but when I kill it, my program no longer freezes. The thread is one of the CreateApplicationContext threads, here is the last few items in the stack trace of that thread. 6 ntkrnlpa.exe+0x897bc 7 ntdll.dll!KiFastSystemCallRet 8 mscorwrks.dll!LogHelp_TerminateOnAssert+0x61 9 mscorwrks.dll!DllUnregisterServerInternal+0x10523 10 mscorwrks.dll!DllUnregisterServerInternal+0x10542 11 mscorwrks.dll!StrongNameErrorInfo+0x34387 12 mscorwrks.dll!StrongNameErrorInfo+0x34815 13 mscorwrks.dll!CreateApplicationContext+0xbc35 14 KERNEL32.dll!GetModuleHandleA+0xdf Process explorer says my program is using no CPU nor throwing any exceptions while it is hung.

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Extending abstract classes in c#

- by ng

I am a Java developer and I have noticed some differences in extending abstract classes in c# as opposed to Java. I was wondering how a c# developer would achived the following. 1) Covarience public abstract class A { public abstract List<B> List(); } public class BList : List<T> where T : B { } public abstract class C : A { public abstract BList List(); } So in the above hierarchy, there is covarience in C where it returns a type compatible with what A returns. However this gives me an error in Visual Studio. Is there a way to specify a covarient return type in c#? 2) Adding a setter to a property public abstract class A { public abstract String Name { get; } } public abstract class B : A { public abstract String Name { get; set } } Here the compiler complains of hiding. Any suggestions? Please do not suggest using interfaces unless that is the ONLY way to do this.

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WPF Calling a custom command on a custom control (from a viewmodel?)

- by user190615

I want to take a snap of the visual tree of a custom wpf control when the user clicks a button in a toolbar. The control is bound to a viewmodel. I have a BitmapSource dp in the custom control holding the snapped image which is bound to a property on my VM. The BitmapSource dp on the control is updated via a custom command on the control. I've tied the toolbar button's command to call the controls command which updates the BitmapSource. Now the problem is the end result I want is when the user clicks the button, the control updates its image and then the vm offers to save this image. I cant wrap my mind around an mvvm way of doing this. One inelegant solution is that control fires an event after the image is updated which is routed to the viewmodel as a command(command behavior) but then if i want to do something else with the image on some other button click, all the commands bound to the events will fire. All thoughts appreciated. EDIT The command on the control is a RoutedCommand and the commands in my vm are Prism delegate commands.

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URL path changes between dev and published version

- by Bob Horn

I just got Scott Hanselman's chat app with SignalR working with ASP.NET MVC 4. After hours of configuration, trial and error, and getting different versions of Windows to talk to each other on my home network, it's all working except that I'm left with one issue that I'm not sure how to handle. This line of javascript has to change, depending on if I'm running the app through Visual Studio or the published (IIS) version: Works when running within VS: var connection = $.connection('echo'); Works with published version: var connection = $.connection('ChatWithSignalR/echo'); When I run within VS, the URL is: http://localhost:9145/ And the published version is: http://localhost/ChatWithSignalR If I don't change that line of code, and try to run the app within VS, using the javascript that has ChatWithSignalR in it, I get an error like this: Failed to load resource: the server responded with a status of 404 (Not Found) http://localhost:9145/ChatWithSignalR/echo/negotiate?_=1347809290826 What can I do so that I can use the same javascript code and have it work in both scenarios? var connection = $.connection('??????'); Note, this is in my Global.asax.cs: RouteTable.Routes.MapConnection<MyConnection>("echo", "echo/{*operation}");

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Huge burst of memory in c# service, what could be the cause?

- by Daniel

I'm working on a c# service application and i have this problem where out of no where and for no obvious reason, the memory for the process will climb from 150mb to almost 2gb in about 5 seconds and then back to 150mb. But nothing in our system should be using any where near that amount of memory (so its probably a bug somewhere). It might be a tight while true loop somewhere but the cpu usage at the time was very low so i thought i'd look for other ideas. Now the weirder thing is when i compile the service for 64bit, the same massive burst will occur except it exceeded 10gb of ram (paging most of it) and it just caused lots of problems with the computer and everything running on it. After a while it shuts down but it looks like windows is still willing to give it more memory. Would you have any ideas or tools that i can use in order to find this? Yes it has lots of logging however nothing in the logs stand out as to why this is happening. I can run the service in a console app mode, so my next test was going to be running it in visual studio debugger and see if i can find anything. It only happens occasionally but usually about 10-20 minutes after startup. On 32bit mode it cleans up and continues on like normally. 64bit mode it crashes after a while and uses stupid amounts of memory. But i'm really stumped as to why this is happening!!!

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Passing a string to a function in C++

- by Chef Flambe

I want to pass a string like "Celcius" into a function that I have but I keep getting errors tossed back at me from the Function. System::Console::WriteLine' : none of the 19 overloads could convert all the argument types I figure I just have something simple wrong. Can someone point out my mistake please? Using MS Visual C++ 2010 I've posted the offending code. The other functions (not posted) work fine. void PrintResult( double result, std::string sType ); // Print result and string // to the console //============================================================================================= // start of main //============================================================================================= void main( void ) { ConsoleKeyInfo CFM; // Program Title and Description ProgramDescription(); // Menu Selection and calls to data retrieval/calculation/result Print CFM=ChooseFromMenu(); switch(CFM.KeyChar) // ************************************************************ { //* case '1' : PrintResult(F2C(GetTemperature()),"Celsius"); //* break; //* //* case '2' : PrintResult(C2F(GetTemperature()),"Fahrenheit"); //* break; //* //* default : Console::Write("\n\nSwitch : Case !!!FAILURE!!!"); //* } //************************************************************ system("pause"); return; } //Function void PrintResult( double result, std::string sType ) { Console::WriteLine("\n\nThe converted temperature is {0:F2} degrees {1}\n\n",result,sType); return; }

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Performance issue between builds

- by DeadMG

I've been developing a small indie game in my spare time and have run across an inexplicable issue. Some builds of the game will randomly run several hundred frames per second slower than other builds. For example, when rendering some text and no 3D scene, I can achieve 1800FPS on my own hardware. Add one 3D sphere (10k verts, pixel shaded), achieve 1700 FPS. Add two more spheres, achieve 800 FPS. Remove all spheres, achieve 1100FPS- even though the code now renders the same scene as I previously achieved at 1800FPS, which is just the FPS counter being rendered. I've tried rebuilding and cleaning the project and rebooting the compiler. This is in Release mode and I turned on all the optimizations I could find. Any suggestions as to the cause? I ran a quick profile, and Visual Studio seems to think that over 90% of my time was spent in D3D9_43.dll, suggesting that it's not a bug in my app, which doesn't explain why it manifests in only some builds. I rebooted my machine and it's back up to 1800FPS. I think it's a bug in the DirectX SDK tools (amongst many others). Going to delete this question.

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Deserializing child elements as attributes of parent

- by LloydPickering

I have XML files which I need to deserialize. I used the XSD tool from Visual Studio to create c# object files. the generated classes do deserialize the files except not in the way which I need. I would appreciate any help figuring out how to solve this problem. The child elements named 'data' should be attributes of the parent element 'task'. A shortened example of the XML is below: <task type="Nothing" id="2" taskOnFail="false" > <data value="" name="prerequisiteTasks" /> <data value="" name="exclusionTasks" /> <data value="" name="allowRepeats" /> <task type="Wait for Tasks" id="10" taskOnFail="false" > <data value="" name="prerequisiteTasks" /> <data value="" name="exclusionTasks" /> <data value="" name="allowRepeats" /> </task> <task type="Wait for Tasks" id="10" taskOnFail="false" > <data value="" name="prerequisiteTasks" /> <data value="" name="exclusionTasks" /> <data value="" name="allowRepeats" /> </task> </task> The Class definition I am trying to deserialize to is in the form: public class task { public string prerequisiteTasks {get;set;} public string exclusionTasks {get;set;} public string allowRepeats {get;set;} [System.Xml.Serialization.XmlElementAttribute("task")] public List<task> ChildTasks {get;set;} } The child 'task's are fine, but the generated files put the 'data' elements into an array of data[] rather than as named members of the task class as I need.

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C# Script to get modified date from URL directory

- by Jynx

Hello, I am fairly new to C# and was hoping for some assistance. I currently use Visual Studio 2008. What I am wanting to do is the following: I have a server (\backupserv) that runs a RoboCopy script nightly to backup directories from 18 other servers. These directories are then copied down to \backup in directories of their own: Example: It copies down "Dir1", "Dir2", and "Dir3" from Server1 into \backupserv\backups\Server1 into their own directories (\backupserv\backups\Server1\Dir1, \backupserv\backups\Server1\Dir2, and \backupserv\backups\Server1\Dir3). It does this for all 18 servers nightly between 12am and 6am. The RoboCopy runs via schedule task. A log file is created in \backupserv\backups\log and is named server1-dir1.log, server1-dir2.log, etc. What I am wanting to accomplish in C# is the ability to have a 'report' showing the modified date of each text log file. To do this I need to browse the \backupserv\backups\log directory, determine the modified date, and have a report displayed (prefer HTML if possible). Along with the modified date I will be showing more information, but that is later. Again, I am fairly new to C#, so, please be gentle. I was referred here by another programmer, and was told I would get some assistance. Thanks in advance. If I have missed any detail please let me know and I will do my best to answer.

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Understanding Basic Prototyping & Updating Key/Value pairs

- by JordanD

First time poster, long time lurker. I'm trying to learn some more advanced features of .js, and have two ojectives based on the pasted code below: I would like to add methods to a parent class in a specific way (by invoking prototype). I intend to update the declared key/value pairs each time I make an associated method call. execMTAction as seen in TheSuper will execute each function call, regardless. This is by design. Here is the code: function TheSuper(){ this.options = {componentType: "UITabBar", componentName: "Visual Browser", componentMethod: "select", componentValue: null}; execMTAction(this.options.componentType, this.options.componentName, this.options.componentMethod, this.options.componentValue); }; TheSuper.prototype.tapUITextView = function(val1, val2){ this.options = {componentType: "UITextView", componentName: val1, componentMethod: "entertext", componentValue: val2}; }; I would like to execute something like this (very simple): theSuper.executeMTAction(); theSuper.tapUITextView("a", "b"); Unfortunately I am unable to overwrite the "this.options" in the parent, and the .tapUITextView method throws an error saying it cannot find executeMTAction. All I want to do, like I said, is to update the parameters in the parent, then have executeMTAction run each time I make any method call. That's it. Any thoughts? I understand this is basic but I'm coming from a long-time procedural career and .js seems to have this weird confluence of oo/procedural that I'm having a bit of difficulty with. Thanks for any input!

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C++: What is the size of an object of an empty class?

- by Ashwin

I was wondering what could be the size of an object of an empty class. It surely could not be 0 bytes since it should be possible to reference and point to it like any other object. But, how big is such an object? I used this small program: #include <iostream> using namespace std; class Empty {}; int main() { Empty e; cerr << sizeof(e) << endl; return 0; } The output I got on both Visual C++ and Cygwin-g++ compilers was 1 byte! This was a little surprising to me since I was expecting it to be of the size of the machine word (32 bits or 4 bytes). Can anyone explain why the size of 1 byte? Why not 4 bytes? Is this dependent on compiler or the machine too? Also, can someone give a more cogent reason for why an empty class object will not be of size 0 bytes?

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C++ unrestricted union workaround

- by Chris

#include <stdio.h> struct B { int x,y; }; struct A : public B { // This whines about "copy assignment operator not allowed in union" //A& operator =(const A& a) { printf("A=A should do the exact same thing as A=B\n"); } A& operator =(const B& b) { printf("A = B\n"); } }; union U { A a; B b; }; int main(int argc, const char* argv[]) { U u1, u2; u1.a = u2.b; // You can do this and it calls the operator = u1.a = (B)u2.a; // This works too u1.a = u2.a; // This calls the default assignment operator >:@ } Is there any workaround to be able to do that last line u1.a = u2.a with the exact same syntax, but have it call the operator = (don't care if it's =(B&) or =(A&)) instead of just copying data? Or are unrestricted unions (not supported even in Visual Studio 2010) the only option?

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