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  • How to delete characters and append strings?

    - by devin250
    i am adding a new record to xml file im first quering all existing items and storing the count in an int int number = query.count() and then incrementing number by 1; number = number +1; now i want to format this value in a string having "N00000000" format and the number will ocuppy the last positions Pseudo code: //declare the format string sting format = "N00000000" //calculate the length of number string int length =number.ToString().Length(); // delete as many characters from right to left as the length of number string ??? // finally concatenate both strings with + operator ??? help please

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  • R adding infrequent date 'events' to a time series plot

    - by flyingcrab
    Hi, I am just starting on R - and have hit a bit of a deadlock with some time series data. I have a time series (date and value) in 'zoo' format, that I want to annotate with a cross when an event occurs. The events are irregular and in a csv format (just the dates, sometimes repeated). I've managed to read in the dates etc into a format that R accepts - but i cant seem to get a means to chart the main time series with the secondary events annotated on top?

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  • Rails does not display error messages on a form in a custom method

    - by slythic
    Hi all, I've created a custom method called checkout in my app. I create an order (which is done my adding products to my "cart"), assign it to my client, and then I head to my checkout screen where I confirm the items and enter their customer order number and complete the order (submit). Everything works great except that it doesn't display error messages. I'm able to display a flash error notice (seen in complete_order method) when things go wrong but it doesn't specify the details like a normal form would. The error messages should appear if the customer order number is not unique for that client. Below is the custom method (checkout) related code. Order Model: validates_uniqueness_of :customer_order_number, :scope => :client_id Orders_controller: def checkout @order = current_order end def complete_order @order = current_order respond_to do |format| if @order.update_attributes(params[:order]) @order.complete #sets submitted datetime and state to 'complete' flash[:notice] = 'Thank you! Your order is being processed.' format.html { redirect_to( products_path ) } format.xml { head :ok } else flash[:error] = 'Please review your items' #added to confirm an error is present format.html { redirect_to( checkout_path ) } format.xml { render :xml => @order.errors, :status => :unprocessable_entity } end end end And the form in the checkout view: <% form_for @order, :url => { :controller => "orders", :action => "complete_order" } do |f| %> <%= f.error_messages %> <%= f.text_field :customer_order_number, :label => "Purchase Order Number" %> <p> <%= f.submit 'Complete Order', :confirm => 'Are you sure?' %> <small> or <%= link_to 'cancel', current_cart_path %></small> </p> <% end %> Any idea how I can display the specific error messages? Thank you in advance! -Tony

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  • Are Fortran control characters (carriage control) still implemented in compilers?

    - by CmdrGuard
    In the book Fortran 95/2003 for Scientists and Engineers, there is much talk given to the importance of recognizing that the first column in a format statement is reserved for control characters. I've also seen control characters referred to as carriage control on the internet. To avoid confusion, by control characters, I refer to the characters "1, a blank (i.e. \s), 0, and +" as having an effect on the vertical spacing of output when placed in the first column (character) of a FORMAT statement. Also, see this text-only web page written entirely in fixed-width typeface : Fortran carriage-control (because nothing screams accuracy and antiquity better than prose in monospaced font). I found this page and others like it to be not quite clear. According to Fortran 95/2003 for Scientists and Engineers, failure to recall that the first column is reserved for carriage control can lead to horrible unintended output. Paraphrasing Dave Barry, type the wrong character, and nuclear missiles get fired at Norway. However, when I attempt to adhere to this stern warning, I find that gfortran has no idea what I'm talking about. Allow me to illustrate my point with some example code. I am trying to print out the number Pi: PROGRAM test_format IMPLICIT NONE REAL :: PI = 2 * ACOS(0.0) WRITE (*, 100) PI WRITE (*, 200) PI WRITE (*, 300) PI 100 FORMAT ('1', "New page: ", F11.9) 200 FORMAT (' ', "Single Space: ", F11.9) 300 FORMAT ('0', "Double Space: ", F11.9) END PROGRAM test_format This is the output: 1New page: 3.141592741 Single Space: 3.141592741 0Double Space: 3.141592741 The "1" and "0" are not typos. It appears that gfortran is completely ignoring the control character column. My question, then, is this: Are control characters still implemented in standards compliant compilers or is gfortran simply not standards compliant? For clarity, here is the output of my gfortran -v Using built-in specs. Target: powerpc-apple-darwin9 Configured with: ../gcc-4.4.0/configure --prefix=/sw --prefix=/sw/lib/gcc4.4 --mandir=/sw/share/man --infodir=/sw/share/info --enable-languages=c,c++,fortran,objc,java --with-gmp=/sw --with-libiconv-prefix=/sw --with-ppl=/sw --with-cloog=/sw --with-system-zlib --x-includes=/usr/X11R6/include --x-libraries=/usr/X11R6/lib --disable-libjava-multilib --build=powerpc-apple-darwin9 --host=powerpc-apple-darwin9 --target=powerpc-apple-darwin9 Thread model: posix gcc version 4.4.0 (GCC)

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  • MS Access 2003 - Formatting results in a list box problem.

    - by Justin
    So I have a list box that displays averages in a table like format from a crossyab query. It's just what I need the query is right, there is just one thing. I had to set the field properties in the query as format: standard..decimal:2. Which is exactly what I needed. However..the list box will not pick up on this. First I typed the crosstab sql into the list box's properties....and then I ran into this problem. So then I actually just created the query object, saved it and set that as the rowsource for the list box. Still won't work....when I open the query it is the correct format. So is there a way to further format a text box? Is there a way tell it to limit decimal places to one or two on returned values? Thanks!

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  • Excel 2010 Access to path is denied temp

    - by Chris Anderson
    I am using excel data reader to read data from an excel file. FileStream stream = File.Open(filePath, FileMode.Open, FileAccess.Read); //1. Reading from a binary Excel file ('97-2003 format; *.xls) IExcelDataReader excelReader = ExcelReaderFactory.CreateBinaryReader(stream); //2. Reading from a OpenXml Excel file (2007 format; *.xlsx) IExcelDataReader excelReader = ExcelReaderFactory.CreateOpenXmlReader(stream); http://exceldatareader.codeplex.com/ This reads excel 1997-2003 format and excel 2007 format on my local machine and when we move it to our test server. However, when moved to production, it works for excel 97-2003 files, but when I try to read 2007 files I receive the following error: Access to the path 'C:\Documents and Settings\PORTALS03\ASPNET\LOCALS~1\Temp\TMP_Z129388041687919815' is denied. How is it possible that the 97-2003 excel file can be read but the 2007 files throw access is denied?

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  • problem with date in sql CE

    - by Gold
    i have sqlCE DataBase, i have Tdate field (datetime) i notice that his format is: MM/DD/YYYY in my C# program i work with date in: DD/MM/YYYY format. how i can insert to my sqlCE data base my C# format ?

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  • I want to convert NSString to NSDate but UIPickerView shows current date

    - by Ali
    I want to convert NSString to NSDate but UIPickerView shows current datedatePicker=[[UIDatePicker alloc]init]; datePicker.userInteractionEnabled=YES; datePicker.minuteInterval=5; NSLog(@"Date"); //////// NSString *curDate=alarmData.date; //Jan 14, 2011 11:37 NSDateFormatter *format = [[NSDateFormatter alloc] init]; [format setDateFormat:@"MMM dd, yyyy HH:mm"]; //Optionally for time zone converstions [format setTimeZone:[NSTimeZone timeZoneWithName:nil]]; NSDate *da = [format dateFromString:curDate]; [datePicker setDate:da animated:YES]; any suggestions

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  • What are the precise rules/PHP function for encoding strings into POST arrays?

    - by AlexeyMK
    Greetings, Just getting into PHP web development. I've got an HTML form where a user checks some series of dynamically-generated checkboxes, and submits via POST. On the PHP side, I want to check which of the check-boxes were clicked. I have an array $full_list, and am doing something like $selected_checkboxes = array_filter($full_list, function($item) { array_key_exists($item, $_POST); } I run into problems when a list item is named, for example "Peanut Butter", since in the POST array it is named "Peanut_Butter". I could certainly just str_replace " " with "_" before checking array_key_exists, but I imagine that there is a more fundamental encoding problem here; specifically, I'm not sure of exactly what layer transforms normal strings in HTML Forms (value="Peanut Butter") into "Peanut_Butter". So: what layer is responsible for this conversion? Is it the browser? what are the exact conversion rules, and is there a PHP function out there that will replicate that exact conversion? Thanks!

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  • 'Stack level too deep' error in engine-like plugin with globalize

    - by nutsmuggler
    Hello folks. I have built an engine-like plugin thanks to the new features of Rails 2.3. It's a 'Product' module for a CMS, extrapolated from a previously existing (and working) model/controller. The plugin relies on easy_fckeditor and on globalize (description and title field are localised), and I suspect that globalized could be the culprit here... Everything works fine, except for the update action. I get the following error message: (posting just the first lines, all the message is about attribute_methods) stack level too deep /Library/Ruby/Gems/1.8/gems/activerecord-2.3.2/lib/active_record/attribute_methods.rb:64:in `generated_methods?' /Library/Ruby/Gems/1.8/gems/activerecord-2.3.2/lib/active_record/attribute_methods.rb:241:in `method_missing' /Library/Ruby/Gems/1.8/gems/activerecord-2.3.2/lib/active_record/attribute_methods.rb:249:in `method_missing' For referenze, the full error stack is here: http://pastie.org/596546 I've tried to debug eliminating all the input fields, one by one, but I keep getting the error. fckeditor doesn't seem the culprit (error even without fckeditor) This is the action: def update params[:product][:term_ids] ||= [] @product = Product.find(params[:id]) respond_to do |format| if @product.update_attributes(params[:product]) flash[:notice] = t(:Product_was_successfully_updated) format.html { redirect_to products_path } format.xml { head :ok } else format.html { render :action => "edit" } format.xml { render :xml => @product.errors, :status => :unprocessable_entity } end end end As you see it's quite straightforward. Of course I am not hoping someone to solve this question straightaway, I'd just like to have a head up, a suggestion about where to look to solve this issue. Thanks in advance, Davide

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  • Can/Should you throw exceptions in a c# switch statement?

    - by Kettenbach
    Hi All, I have an insert query that returns an int. Based on that int I may wish to throw an exception. Is this appropriate to do within a switch statement? switch (result) { case D_USER_NOT_FOUND: throw new ClientException(string.Format("D User Name: {0} , was not found.", dTbx.Text)); case C_USER_NOT_FOUND: throw new ClientException(string.Format("C User Name: {0} , was not found.", cTbx.Text)); case D_USER_ALREADY_MAPPED: throw new ClientException(string.Format("D User Name: {0} , is already mapped.", dTbx.Text)); case C_USER_ALREADY_MAPPED: throw new ClientException(string.Format("C User Name: {0} , is already mapped.", cTbx.Text)); default: break; } I normally add break statements to switches but they will not be hit. Is this a bad design? Please share any opinions/suggestions with me. Thanks, ~ck in San Diego

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  • image merging using php in GD

    - by vipinsahu
    hi i want to merge to images but the problem is one image is .PNG format and second one is .JPG format and after merging the output should be .PNG format but the transparency is not appearing .plz help Thanks

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  • Is DateTime.ParseExact() faster than DateTime.Parse()

    - by Nassign
    I would like to know if ParseExact is faster than Parse. I think that it should be ParseExact since you already gave the format but I also think all the checking for the Culture info would slow it down. Does microsoft say in any document on performance difference between the two. The format to be used is a generic 'yyyy/MM/dd' format .

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  • No route matches when trying to edit

    - by mmichael
    Here's the scoop: I've created a test app that allows users to create ideas and then add "bubbles" to these ideas. Currently, a bubble is just text. I've successfully linked bubbles to ideas. Furthermore, when a user goes to view an idea it lists all of the bubbles attached to that idea. The user can even delete the bubble for any given idea. My problem lies in editing bubbles. When a user views an idea, he sees the idea's content as well as any bubbles for that idea. As a result, I've set all my bubble controls (editing and deleting) inside the ideas "show" view. My code for editing a bubble for an idea is <%= link_to 'Edit Bubble', edit_idea_bubble_path %>. I ran rake routes to find the correct path for editing bubbles and that is what was listed. Here's my error: No route matches {:action=>"edit", :controller=>"bubbles"} In my bubbles controller I have: def edit @idea = Idea.find(params[:idea_id]) @bubble = @idea.bubbles.find(params[:id]) end def update @idea = Idea.find(params[:idea_id]) @bubble = @idea.bubbles.find(params[:id]) respond_to do |format| if @bubble.update_attributes(params[:bubble]) format.html { redirect_to(@bubble, :notice => 'Bubble was successfully updated.') } format.xml { head :ok } else format.html { render :action => "Edit" } format.xml { render :xml => @bubble.errors, :status => :unprocessable_entity } end end end To go a step further, I have the following in my routes.rb file resources :ideas do resources :bubbles end So far everything seems to function except when I try to edit a bubble. I'd love some guidance. Thanks!

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  • Override transparency color when converting transparent PNG to JPG

    - by Alexander Malfait
    I'm using Dragonfly to generate thumbnail images in a Rails app. I'm serving all picture images as JPG's. Now the client is uploading transparent PNG files, like this one: http://www.ibanez.co.jp/products/images/eg2010/ART120_TRF_12_02.png Dragonfly uses RMagick to convert these images to JPG. The problem is that it converts the PNG images to JPG with a black background, and my site's design requires a white background. I've tried to override it like this: encoded_image = Magick::Image.from_blob(image.data).first if encoded_image.format.downcase == format image # do nothing else encoded_image.format = format encoded_image.background_color = "white" encoded_image.transparent_color = "white" encoded_image.to_blob end But the produced JPG images still contain a black background. Does anyone know how to beat RMagick into using a white background when converting the transparent layer? I know I could just serve as PNG, but then the images are 10 times as large, and the site is already pretty bandwidth heavy.

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  • Dynamically formatting a string

    - by TofuBeer
    Before I wander off and roll my own I was wondering if anyone knows of a way to do the following sort of thing... Currently I am using MessageFormat to create some strings. I now have the requirement that some of those strings will have a variable number of arguments. For example (current code): MessageFormat.format("{0} OR {1}", array[0], array[1]); Now I need something like: // s will have "1 OR 2 OR 3" String s = format(new int[] { 1, 2, 3 }); and: // s will have "1 OR 2 OR 3 OR 4" String s = format(new int[] { 1, 2, 3, 4 }); There are a couple ways I can think of creating the format string, such as having 1 String per number of arguments (there is a finite number of them so this is practical, but seems bad), or build the string dynamically (there are a lot of them so this could be slow). Any other suggestions?

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  • What's with bad function call in view generated via scaffold?

    - by meta
    I've scaffolded Things element: script/generate scaffold wip/thing name:string and got some invalid function call in views, like: <td><%= link_to 'Edit', edit_thing_path(thing) %></td> Which raise this error: ActionView::TemplateError (undefined method `edit_thing_path' for #<ActionView::Base:0xb5c00944>) on line #11 of app/views/wip/things/index.html.erb: 8: <tr> 9: <td><%=h thing.name %></td> 10: <td><%= link_to 'Show', thing %></td> 11: <td><%= link_to 'Edit', edit_thing_path(thing) %></td> 12: <td><%= link_to 'Destroy', thing, :confirm => 'Are you sure?', :method => :delete %></td> 13: </tr> 14: <% end %> What's with that function? Where is it? Is it some kind of automagic stuff or do I need to implement it (if so - where should it go?) I have resource defined in routes with namespace: map.namespace :wip do |wip| wip.resources :things end rake routes gives me this: wip_things GET /wip/things(.:format) {:action=>"index", :controller=>"wip/things"} POST /wip/things(.:format) {:action=>"create", :controller=>"wip/things"} new_wip_thing GET /wip/things/new(.:format) {:action=>"new", :controller=>"wip/things"} edit_wip_thing GET /wip/things/:id/edit(.:format) {:action=>"edit", :controller=>"wip/things"} wip_thing GET /wip/things/:id(.:format) I assumed that those names (wip_thing, new_wip_thing) are the correct names, but it's still gives me that error Thanks.

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  • ASP.NET GridView issue with DataFormatString in a BoundField

    - by David
    I have a BoundField in a GridView whose datatype (in MSSQL) is time(7). The format is being displayed as: hh:mm:ss.xxxxxx I want to add a DataFormatString to this boundfield so that the field displays in the format: hh:mm:ss Here is a snippet of the .aspx file that I'm modifying: <asp:BoundField DataField="ProcTime" HeaderText="ProcTime" SortExpression="ProcTime" ApplyFormatInEditMode="true" HtmlEncode="true" DataFormatString="{0:F0}" /> I've tried many different format strings (t, T, d, D, m, etc) but it does not change the format of the boundfield. What am I missing?

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  • Rails address and routes?

    - by Danny McClelland
    Hi Everyone, I have created a custom action within one of my controlers as follows: # GET /kases/discharge/1 # GET /kases/discharge/1.xml def discharge @kase = Kase.find_by_jobno(params[:id]) respond_to do |format| format.html { } # discharge.html.erb format.xml { render :xml => @kase } format.pdf { render :layout => false } prawnto :prawn => { :background => "#{RAILS_ROOT}/public/images/discharge.png", :left_margin => 0, :right_margin => 0, :top_margin => 0, :bottom_margin => 0, :page_size => 'A4' } end end For the edit actions etc the link would be link_to edit_kase_path(@kase) Is there a way of linking to the discharge action already, or do I have to make a custom route? Thanks, Danny

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  • The markup must be well-formed

    - by Haythem
    Hi, I am beginer in SAX and Java. I am tring to read Information from not well formed XML File. When I try to use SAX or DOM Parser then I have this error: The markup in the document following the root element must be well-formed. My XML File looks like this: <format type="filename" t="13241">0;W650;004;AG-Erzgeb</format> <format type="driver" t="123412">001;023</format> ... Can I force SAX or DOM to parse not well-formed XML files? Thank you for your help. Haythem

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  • Creating a blocking Queue<T> in .NET?

    - by spoon16
    I have a scenario where I have multiple threads adding to a queue and multiple threads reading from the same queue. If the queue reaches a specific size all threads that are filling the queue will be blocked on add until an item is removed from the queue. The solution below is what I am using right now and my question is: How can this be improved? Is there an object that already enables this behavior in the BCL that I should be using? internal class BlockingCollection<T> : CollectionBase, IEnumerable { //todo: might be worth changing this into a proper QUEUE private AutoResetEvent _FullEvent = new AutoResetEvent(false); internal T this[int i] { get { return (T) List[i]; } } private int _MaxSize; internal int MaxSize { get { return _MaxSize; } set { _MaxSize = value; checkSize(); } } internal BlockingCollection(int maxSize) { MaxSize = maxSize; } internal void Add(T item) { Trace.WriteLine(string.Format("BlockingCollection add waiting: {0}", Thread.CurrentThread.ManagedThreadId)); _FullEvent.WaitOne(); List.Add(item); Trace.WriteLine(string.Format("BlockingCollection item added: {0}", Thread.CurrentThread.ManagedThreadId)); checkSize(); } internal void Remove(T item) { lock (List) { List.Remove(item); } Trace.WriteLine(string.Format("BlockingCollection item removed: {0}", Thread.CurrentThread.ManagedThreadId)); } protected override void OnRemoveComplete(int index, object value) { checkSize(); base.OnRemoveComplete(index, value); } internal new IEnumerator GetEnumerator() { return List.GetEnumerator(); } private void checkSize() { if (Count < MaxSize) { Trace.WriteLine(string.Format("BlockingCollection FullEvent set: {0}", Thread.CurrentThread.ManagedThreadId)); _FullEvent.Set(); } else { Trace.WriteLine(string.Format("BlockingCollection FullEvent reset: {0}", Thread.CurrentThread.ManagedThreadId)); _FullEvent.Reset(); } } }

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  • Different cursor formats in IOFrameBufferShared

    - by Thomi
    Hi, I'm reading the moust cursor pixmap data from the StdFBShmem_t structure, as defined in the IOFrameBufferShared API. Everything works fine, 90% of the time. However, I have noticed that some applications on the mac set a cursor in a different format. According to the documentation for the data structures, the cursor pixmap format should always be in the same format as the frame buffer. My frame buffer is 32BPP. I expect the pixmap data to be in the format 0xAARRGGBB, which is it. However, in some cases, I'm reading data that looks like a mask. Specifically, the pixel will either be 0x00FFFFFF or `0x00000000. This looks to me to be a mask for separate pixel data stored somewhere else. As far as I can tell, the only application that uses this cursor pixel format is Qt Creator, but I need to work with all applications, so I'd like to sort this out. The code I'm using to read the cursor pixmap data is: NSAutoreleasePool *autoReleasePool = [[NSAutoreleasePool alloc] init]; NSPoint mouseLocation = [NSEvent mouseLocation]; NSArray *allScreens = [NSScreen screens]; NSEnumerator *screensEnum = [allScreens objectEnumerator]; NSScreen *screen; NSDictionary *screenDesc = nil; while ((screen = [screensEnum nextObject])) { NSRect screenFrame = [screen frame]; screenDesc = [screen deviceDescription]; if (NSMouseInRect(mouseLocation, screenFrame, NO)) break; } if (screen) { kern_return_t err; CGDirectDisplayID displayID = (CGDirectDisplayID) [[screenDesc objectForKey:@"NSScreenNumber"] pointerValue]; task_port_t taskPort = mach_task_self(); io_service_t displayServicePort = CGDisplayIOServicePort(displayID); io_connect_t displayConnection =0; err = IOFramebufferOpen(displayServicePort, taskPort, kIOFBSharedConnectType, &displayConnection); if (KERN_SUCCESS == err) { union { vm_address_t vm_ptr; StdFBShmem_t *fbshmem; } cursorInfo; vm_size_t size; err = IOConnectMapMemory(displayConnection, kIOFBCursorMemory, taskPort, &cursorInfo.vm_ptr, &size, kIOMapAnywhere | kIOMapDefaultCache | kIOMapReadOnly); if (KERN_SUCCESS == err) { // for some reason, cursor data is not always in the same format as the frame buffer. For this reason, we need // some way to detect which structure we should be reading. QByteArray pixData((const char*)cursorInfo.fbshmem->cursor.rgb24.image[currentFrame], m_mouseInfo.currentSize.width() * m_mouseInfo.currentSize.height() * 4); IOConnectUnmapMemory(displayConnection, kIOFBCursorMemory, taskPort, cursorInfo.vm_ptr); } // IOConnectMapMemory else qDebug() << "IOConnectMapMemory Failed:" << err; IOServiceClose(displayConnection); } // IOServiceOpen else qDebug() << "IOFramebufferOpen Failed:" << err; }// if screen [autoReleasePool release]; My question is: How can I detect if the cursor is a different format from the framebuffer? Where can I read the actual pixel data? the bm18Cursor structure contains a mask section, but it's not in the right place for me to be reading it using the code above. Cheers,

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  • C++0x rvalue references - lvalues-rvalue binding

    - by Doug
    This is a follow-on question to http://stackoverflow.com/questions/2748866/c0x-rvalue-references-and-temporaries In the previous question, I asked how this code should work: void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } It seems that the move overload should probably be called because of the implicit temporary, and this happens in GCC but not MSVC (or the EDG front-end used in MSVC's Intellisense). What about this code? void f(std::string &&); //NB: No const string & overload supplied void g1(const char * arg) { f(arg); } void g2(const std::string & arg) { f(arg); } It seems that, based on the answers to my previous question that function g1 is legal (and is accepted by GCC 4.3-4.5, but not by MSVC). However, GCC and MSVC both reject g2 because of clause 13.3.3.1.4/3, which prohibits lvalues from binding to rvalue ref arguments. I understand the rationale behind this - it is explained in N2831 "Fixing a safety problem with rvalue references". I also think that GCC is probably implementing this clause as intended by the authors of that paper, because the original patch to GCC was written by one of the authors (Doug Gregor). However, I don't this is quite intuitive. To me, (a) a const string & is conceptually closer to a string && than a const char *, and (b) the compiler could create a temporary string in g2, as if it were written like this: void g2(const std::string & arg) { f(std::string(arg)); } Indeed, sometimes the copy constructor is considered to be an implicit conversion operator. Syntactically, this is suggested by the form of a copy constructor, and the standard even mentions this specifically in clause 13.3.3.1.2/4, where the copy constructor for derived-base conversions is given a higher conversion rank than other implicit conversions: A conversion of an expression of class type to the same class type is given Exact Match rank, and a conversion of an expression of class type to a base class of that type is given Conversion rank, in spite of the fact that a copy/move constructor (i.e., a user-defined conversion function) is called for those cases. (I assume this is used when passing a derived class to a function like void h(Base), which takes a base class by value.) Motivation My motivation for asking this is something like the question asked in http://stackoverflow.com/questions/2696156/how-to-reduce-redundant-code-when-adding-new-c0x-rvalue-reference-operator-over ("How to reduce redundant code when adding new c++0x rvalue reference operator overloads"). If you have a function that accepts a number of potentially-moveable arguments, and would move them if it can (e.g. a factory function/constructor: Object create_object(string, vector<string>, string) or the like), and want to move or copy each argument as appropriate, you quickly start writing a lot of code. If the argument types are movable, then one could just write one version that accepts the arguments by value, as above. But if the arguments are (legacy) non-movable-but-swappable classes a la C++03, and you can't change them, then writing rvalue reference overloads is more efficient. So if lvalues did bind to rvalues via an implicit copy, then you could write just one overload like create_object(legacy_string &&, legacy_vector<legacy_string> &&, legacy_string &&) and it would more or less work like providing all the combinations of rvalue/lvalue reference overloads - actual arguments that were lvalues would get copied and then bound to the arguments, actual arguments that were rvalues would get directly bound. Questions My questions are then: Is this a valid interpretation of the standard? It seems that it's not the conventional or intended one, at any rate. Does it make intuitive sense? Is there a problem with this idea that I"m not seeing? It seems like you could get copies being quietly created when that's not exactly expected, but that's the status quo in places in C++03 anyway. Also, it would make some overloads viable when they're currently not, but I don't see it being a problem in practice. Is this a significant enough improvement that it would be worth making e.g. an experimental patch for GCC?

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  • Exporting WPF DataGrid to a text file in a nice looking format. Text file must be easy to read.

    - by Andrew
    Hi, Is there a simple way to export a WPF DataGrid to a text file and a .csv file? I've done some searching and can't see that there is a simple DataGrid method to do so. I have got something working (barely) by making use of the ItemsSource of the DataGrid. In my case, this is an array of structs. I do something with StreamWriters and StringBuilders (details available) and basically have: StringBuilder destination = new StringBuilder(); destination.Append(row.CreationDate); destination.Append(seperator); // seperator is '\t' or ',' for csv file destination.Append(row.ProcId); destination.Append(seperator); destination.Append(row.PartNumber); destination.Append(seperator); I do this for each struct in the array (in a loop). This works fine. The problem is that it's not easy to read the text file. The data can be of different lengths within the same column. I'd like to see something like: 2007-03-03 234238423823 823829923 2007-03-03 66 99 And of course, I get something like: 2007-03-03 234238423823 823829923 2007-03-03 66 99 It's not surprising giving that I'm using Tab delimiters, but I hope to do better. It certainly is easy to read in the DataGrid! I could of course have some logic to pad short values with spaces, but that seems quite messy. I thought there might be a better way. I also have a feeling that this is a common problem and one that has probably been solved before (hopefully within the .NET classes themselves). Thanks.

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  • std::string.resize() and std::string.length()

    - by dreamlax
    I'm relatively new to C++ and I'm still getting to grips with the C++ Standard Library. To help transition from C, I want to format a std::string using printf-style formatters. I realise stringstream is a more type-safe approach, but I find myself finding printf-style much easier to read and deal with (at least, for the time being). This is my function: using namespace std; string formatStdString(const string &format, ...) { va_list va; string output; size_t needed; size_t used; va_start(va, format); needed = vsnprintf(&output[0], 0, format.c_str(), va); output.resize(needed + 1); // for null terminator?? used = vsnprintf(&output[0], output.capacity(), format.c_str(), va); // assert(used == needed); va_end(va); return output; } This works, kinda. A few things that I am not sure about are: Do I need to make room for a null terminator, or is this unnecessary? Is capacity() the right function to call here? I keep thinking length() would return 0 since the first character in the string is a '\0'. Occasionally while writing this string's contents to a socket (using its c_str() and length()), I have null bytes popping up on the receiving end, which is causing a bit of grief, but they seem to appear inconsistently. If I don't use this function at all, no null bytes appear.

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