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  • How to create C++ istringstream from a char array with null(0) characters?

    - by Morpheus
    I have a char array which contains null characters at random locations. I tried to create an iStringStream using this array (encodedData_arr) as below, I use this iStringStream to insert binary data(imagedata of Iplimage) to a MySQL database blob field(using MySQL Connector/C++'s setBlob(istream *is) ) it only stores the characters upto the first null character. Is there a way to create an iStringStream using a char array with null characters? unsigned char *encodedData_arr = new unsigned char[data_vector_uchar->size()]; // Assign the data of vector<unsigned char> to the encodedData_arr for (int i = 0; i < vec_size; ++i) { cout<< data_vector_uchar->at(i)<< " : "<< encodedData_arr[i]<<endl; } // Here the content of the encodedData_arr is same as the data_vector_uchar // So char array is initializing fine. istream *is = new istringstream((char*)encodedData_arr, istringstream::in || istringstream::binary); prepStmt_insertImage->setBlob(1, is); // Here only part of the data is stored in the database blob field (Upto the first null character)

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  • How can I write a null ASCII character (nul) to a file with a Windows batch script?

    - by Matthew Murdoch
    I'm attempting to write an ASCII null character (nul) to a file from a Windows batch script without success. I initially tried using echo like this: echo <Alt+2+5+6> which seems like it should work (typing <Alt+2+5+6> in the command window does write a null character - or ^@ as it appears), but echo then outputs: More? and hangs until I press <Return>. As an alternative I tried using: copy con tmp.txt >nul <Alt+2+5+6><Ctrl+Z> which does exactly what I need, but only if I type it manually in the command window. If I run it from a batch file it hangs until I press <Ctrl+Z> but even then the output file is created but remains empty. I really want the batch file to stand alone without requiring (for example) a separate file containing a null character which can be copied when needed.

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  • Getting Null value with JSON from MySQL, how to retrive data from MySQL to JSON correctly?

    - by sky
    I'm using following code but cannot return data from MySQL. This is the output: <script type="text/javascript"> var somethings= [null,null,null]; </script> It does have three post, but I couldn't get the title(message) output. EDIT: this is the code I'm using: <?php $session = mysql_connect('localhost','name','pass'); mysql_select_db('dbname', $session); $result= mysql_query('SELECT * FROM posts', $session); $somethings= array(); while ($row= mysql_fetch_assoc($result)) { $somethings[]= $row['something']; } ?> <script type="text/javascript"> var somethings= <?php echo json_encode($somethings); ?>; </script> This is the table: message Try iPhone post! Welcome to Yo~ :) ??!

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  • Why does String.Equals(Object obj) check to see if this == null?

    - by m-y
    // Determines whether two strings match. [ReliabilityContract(Consistency.WillNotCorruptState, Cer.MayFail)] public override bool Equals(Object obj) { //this is necessary to guard against reverse-pinvokes and //other callers who do not use the callvirt instruction if (this == null) throw new NullReferenceException(); String str = obj as String; if (str == null) return false; if (Object.ReferenceEquals(this, obj)) return true; return EqualsHelper(this, str); } The part I don't understand is the fact that it is checking for the current instance, this, against null. The comment is a bit confusing, so I was wondering what does that comment actually mean? Can anyone give an example of how this could break if that check was not there, and does this mean that I should also place that check in my classes?

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  • Null Value Statement

    - by Sam
    Hi All, I have created a table called table1 and it has 4 columns named Name,ID,Description and Date. I have created them like Name varchar(50) null, ID int null,Description varchar(50) null, Date datetime null I have inserted a record into the table1 having ID and Description values. So Now my table1 looks like this: Name ID Description Date Null 1 First Null One of them asked me to modify the table such a way that The columns Name and Date should have Null values instead of Text Null. I don't know what is the difference between those I mean can anyone explain me the difference between these select statements: SELECT * FROM TABLE1 WHERE NAME IS NULL SELECT * FROM TABLE1 WHERE NAME = 'NULL' SELECT * FROM TABLE1 WHERE NAME = ' ' Can anyone explain me?

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  • Automapper: Handling NULL members

    - by PSteele
    A question about null members came up on the Automapper mailing list.  While the problem wasn’t with Automapper, investigating the issue led to an interesting feature in Automapper. Normally, Automapper ignores null members.  After all, what is there really to do?  Imagine these source classes: public class Source { public int Data { get; set; } public Address Address { get; set; } }   public class Destination { public string Data { get; set; } public Address Address { get; set; } }   public class Address { public string AddressType { get; set; } public string Location { get; set; } } And imagine a simple mapping example with these classes: Mapper.CreateMap<Source, Destination>();   var source = new Source { Data = 22, Address = new Address { AddressType = "Home", Location = "Michigan", }, };   var dest = Mapper.Map<Source, Destination>(source); The variable ‘dest’ would have a complete mapping of the Data member and the Address member. But what if the source had no address? Mapper.CreateMap<Source, Destination>();   var source = new Source { Data = 22, };   var dest = Mapper.Map<Source, Destination>(source); In that case, Automapper would just leave the Destination.Address member null as well.  But what if we always wanted an Address defined – even if it’s just got some default data?  Use the “NullSubstitute” option: Mapper.CreateMap<Source, Destination>() .ForMember(d => d.Address, o => o.NullSubstitute(new Address { AddressType = "Unknown", Location = "Unknown", }));   var source = new Source { Data = 22, };   var dest = Mapper.Map<Source, Destination>(source); Now, the ‘dest’ variable will have an Address defined with a type and location of “Unknown”.  Very handy! Technorati Tags: .NET,Automapper,NULL

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  • Problems with subversion (in gnome keyring, maybe), user=null

    - by Tom Brito
    I'm having a problem with my subversion in Ubuntu, and it's happening only on my computer, my colleagues are working fine. It asks for password for user "(null)": Password for '(null)' GNOME keyring: entering the password it shows: svn: OPTIONS of 'http://10.0.203.3/greenfox': authorization failed: Could not authenticate to server: rejected Basic challenge (http://10.0.203.3) What can be causing that (again: it's just on my computer, the svn server is ok).

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  • Adding Column to a SQL Server Table

    - by Dinesh Asanka
    Adding a column to a table is  common task for  DBAs. You can add a column to a table which is a nullable column or which has default values. But are these two operations are similar internally and which method is optimal? Let us start this with an example. I created a database and a table using following script: USE master Go --Drop Database if exists IF EXISTS (SELECT 1 FROM SYS.databases WHERE name = 'AddColumn') DROP DATABASE AddColumn --Create the database CREATE DATABASE AddColumn GO USE AddColumn GO --Drop the table if exists IF EXISTS ( SELECT 1 FROM sys.tables WHERE Name = 'ExistingTable') DROP TABLE ExistingTable GO --Create the table CREATE TABLE ExistingTable (ID BIGINT IDENTITY(1,1) PRIMARY KEY CLUSTERED, DateTime1 DATETIME DEFAULT GETDATE(), DateTime2 DATETIME DEFAULT GETDATE(), DateTime3 DATETIME DEFAULT GETDATE(), DateTime4 DATETIME DEFAULT GETDATE(), Gendar CHAR(1) DEFAULT 'M', STATUS1 CHAR(1) DEFAULT 'Y' ) GO -- Insert 100,000 records with defaults records INSERT INTO ExistingTable DEFAULT VALUES GO 100000 Before adding a Column Before adding a column let us look at some of the details of the database. DBCC IND (AddColumn,ExistingTable,1) By running the above query, you will see 637 pages for the created table. Adding a Column You can add a column to the table with following statement. ALTER TABLE ExistingTable Add NewColumn INT NULL Above will add a column with a null value for the existing records. Alternatively you could add a column with default values. ALTER TABLE ExistingTable Add NewColumn INT NOT NULL DEFAULT 1 The above statement will add a column with a 1 value to the existing records. In the below table I measured the performance difference between above two statements. Parameter Nullable Column Default Value CPU 31 702 Duration 129 ms 6653 ms Reads 38 116,397 Writes 6 1329 Row Count 0 100000 If you look at the RowCount parameter, you can clearly see the difference. Though column is added in the first case, none of the rows are affected while in the second case all the rows are updated. That is the reason, why it has taken more duration and CPU to add column with Default value. We can verify this by several methods. Number of Pages The number of data pages can be obtained by using DBCC IND command. Though, this an undocumented dbcc command, many experts are ok to use this command in production. However, since there is no official word from Microsoft, use this “at your own risk”. DBCC IND (AddColumn,ExistingTable,1) Before Adding the Columns 637 Adding a Column with NULL 637 Adding a column with DEFAULT value 1270 This clearly shows that pages are physically modified. Please note, a high value indicated in the Adding a column with DEFAULT value  column is also a result of page splits. Continues…

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  • Save programmatically created Mesh to .X Files using SlimDX throw null exception

    - by zionpi
    Mesh has been created properly using SlimDX,but when I use the following line: Mesh.ToXFile(barMesh, "foo.x", XFileFormat.Text,CharSet.Unicode); It throws NullReferenceException,through monitor window I can see barMesh is not null, inside the mesh structrue, SkinInfo is null. If SkinInfo is the problem,then how can I initialize it properly?Internet doesn't seems have much information on this.

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  • Is it possible that an insert would use parallelism?

    - by Lieven Cardoen
    In what situation can inserting a simple record (the table has got some 10 columns, two of them are xml) use parallelism? CREATE TABLE [dbo].[PackageSessions]( [PackageSessionId] [int] IDENTITY(1,1) NOT NULL, [PackageId] [int] NOT NULL, [UserId] [int] NOT NULL, [StartDateTime] [datetime] NULL, [StopDateTime] [datetime] NULL, [Score] [float] NOT NULL, [ScoreMax] [float] NOT NULL, [CompletionStatus] [int] NOT NULL, [ReviewPlayerContextId] [int] NOT NULL, [PlayerContextId] [int] NOT NULL, [ReducedScore] [float] NOT NULL, [ReducedScoreMax] [float] NOT NULL, [PackageSnapShot] [xml] NULL, [InterfaceLanguageId] [int] NOT NULL, [Data] [xml] NULL, [PackageSessionLanguageId] [int] NOT NULL, CONSTRAINT [PackageSessions_PK] PRIMARY KEY CLUSTERED ( [PackageSessionId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY]

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  • Drop Down list null value not working for selected text c#?

    - by Tamara JQ
    Hi guys, Basically I have a drop down list which is populated with text and values depending on a selected index of a radio button list. The code is as follows: protected void RBLGender_SelectedIndexChanged(object sender, EventArgs e) { DDLTrous.Items.Clear(); DDLShoes.Items.Clear(); if (RBLGender.SelectedValue.Equals("Male")) { String[] MaleTrouserText = {"[N/A]", "28\"", "30\"", "32\"", "34\"", "36\"", "38\"", "40\"", "42\"", "44\"", "48\""}; String[] MaleTrouserValue = { null, "28\"", "30\"", "32\"", "34\"", "36\"", "38\"", "40\"", "42\"", "44\"", "48\"" }; String[] MaleShoeText = { "[N/A]", "38M", "39M", "40M", "41M", "42M", "43M", "44M", "45M", "46M", "47M" }; String[] MaleShoeValue = { null, "38M", "39M", "40M", "41M", "42M", "43M", "44M", "45M", "46M", "47M" }; for (int i = 0; i < MaleTrouserText.Length; i++) { ListItem MaleList = new ListItem(MaleTrouserText[i], MaleTrouserValue[i]); DDLTrous.Items.Add(MaleList); } for (int i = 0; i < MaleShoeText.Length; i++) { ListItem MaleShoeList = new ListItem(MaleShoeText[i], MaleShoeValue[i]); DDLShoes.Items.Add(MaleShoeList); } } else if (RBLGender.SelectedValue.Equals("Female"))` When the text '[N/A]' is selected I want the value NULL to be inserted into the database. At present when '[N/A]' is selected the value entered into the database is [N/A] does anyone know why? Thanks in advance.

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  • Can a WPF ComboBox display alternative text when its selection is null?

    - by Garth T Kidd
    G'day! I want my WPF ComboBox to display some alternative text when its data-bound selection is null. The view model has the expected properties: public ThingoSelectionViewModel : INotifyPropertyChanged { public ThingoSelectionViewModel(IProvideThingos) { this.Thingos = IProvideThingos.GetThingos(); } public ObservableCollection<Thingo> Thingos { get; set; } public Thingo SelectedThingo { get { return this.selectedThingo; } set { // set this.selectedThingo and raise the property change notification } // ... } The view has XAML binding to the view model in the expected way: <ComboBox x:Name="ComboboxDrive" SelectedItem="{Binding Path=SelectedThingo}" IsEditable="false" HorizontalAlignment="Left" MinWidth="100" IsReadOnly="false" Style="{StaticResource ComboboxStyle}" Grid.Column="1" Grid.Row="1" Margin="5" SelectedIndex="0"> <ComboBox.ItemsSource> <CompositeCollection> <ComboBoxItem IsEnabled="False">Select a thingo</ComboBoxItem> <CollectionContainer Collection="{Binding Source={StaticResource Thingos}}" /> </CompositeCollection> </ComboBox.ItemsSource> </ComboBox> The ComboBoxItem wedged into the top is a way to get an extra item at the top. It's pure chrome: the view model stays pure and simple. There's just one problem: the users want "Select a thingo" displayed whenever the ComboBox' selection is null. The users do not want a thingo selected by default. They want to see a message telling them to select a thingo. I'd like to avoid having to pollute the viewmodel with a ThingoWrapper class with a ToString method returning "Select a thingo" if its .ActualThingo property is null, wrapping each Thingo as I populate Thingos, and figuring out some way to prevent the user from selecting the nulled Thingo. Is there a way to display "Select a thingo" within the ComboBox' boundaries using pure XAML, or pure XAML and a few lines of code in the view's code-behind class?

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  • Should I make the Cells in a Tiledmap as null when my player hits it

    - by Vishal Kumar
    I am making a Tile Based game using Libgdx. I took the idea from SuperKoalio platformer demo by Mario Zencher. When I wanted to implement Collectables in my game , I simply draw the coins using Tiled Map Editor. When my player hits that, I use to set that cell as null. Someday on this site suggested me not to do so... never use null. I agreed. What can be any other way. If I am using layer.setCell(x,y) to set the cell to any other cell... even if an transparent one .. my player seems to be stopped by an invisible object/hurdle. This is my code: for (Rectangle tile : tiles) { if (koalaRect.overlaps(tile)) { TiledMapTileLayer layer = (TiledMapTileLayer) map.getLayers().get(1); try{ type = layer.getCell((int) tile.x, (int) tile.y).getTile().getProperties().get("tileType").toString(); } catch(Exception e){ System.out.print("Exception in Tiles Property"+e); type="nonbreakable"; } //Let us destroy this cell if(("award".equals(type))){ layer.setCell((int) tile.x, (int) tile.y, null); listener.coin(); score+=100; test = ""+layer.getCell(0, 0).getTile().getProperties().get("tileType"); } //DOING THIS GIVES A BAD EFFECT if(("killer".equals(type))){ //player.health--; //layer.setCell((int) tile.x, (int) tile.y, layer.getCell(20,0)); } // we actually reset the player y-position here // so it is just below/above the tile we collided with // this removes bouncing :) if (player.velocity.y > 0) { player.position.y = (tile.y - Player.height); } Is this a right approach? OR I should create separate Sprite Class called Coin.

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  • Matching the superclass's constructor's parameter list, is treating a null default value as a non-null value within a constructor a violation of LSP?

    - by Panzercrisis
    I kind of ran into this when messing around with FlashPunk, and I'm going to use it as an example. Essentially the main sprite class is pretty much class Entity. Entity's constructor has four parameters, each with a default value. One of them is graphic, whose default value is null. Entity is designed to be inherited from, with many such subclasses providing their own graphic within their own internal workings. Normally these subclasses would not have graphic in their constructor's parameter lists, but would simply pick something internally and go with it. However I was looking into possibly still adhering to the Liskov Substitution Principal. Which led me to the following example: package com.blank.graphics { import net.flashpunk.*; import net.flashpunk.graphics.Image; public class SpaceGraphic extends Entity { [Embed(source = "../../../../../../assets/spaces/blank.png")] private const BLANK_SPACE:Class; public function SpaceGraphic(x:Number = 0, y:Number = 0, graphic:Graphic = null, mask:Mask = null) { super(x, y, graphic, mask); if (!graphic) { this.graphic = new Image(BLANK_SPACE); } } } } Alright, so now there's a parameter list in the constructor that perfectly matches the one in the super class's constructor. But if the default value for graphic is used, it'll exhibit two different behaviors, depending on whether you're using the subclass or the superclass. In the superclass, there won't be a graphic, but in the subclass, it'll choose the default graphic. Is this a violation of the Liskov Substitution Principal? Does the fact that subclasses are almost intended to use different parameter lists have any bearing on this? Would minimizing the parameter list violate it in a case like this? Thanks.

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  • TSQL Help (SQL Server 2005)

    - by Mick Walker
    I have been playing around with a quite complex SQL Statement for a few days, and have gotten most of it working correctly. I am having trouble with one last part, and was wondering if anyone could shed some light on the issue, as I have no idea why it isnt working: INSERT INTO ExistingClientsAccounts_IMPORT SELECT DISTINCT cca.AccountID, cca.SKBranch, cca.SKAccount, cca.SKName, cca.SKBase, cca.SyncStatus, cca.SKCCY, cca.ClientType, cca.GFCID, cca.GFPID, cca.SyncInput, cca.SyncUpdate, cca.LastUpdatedBy, cca.Deleted, cca.Branch_Account, cca.AccountTypeID FROM ClientsAccounts AS cca INNER JOIN (SELECT DISTINCT ClientAccount, SKAccount, SKDesc, SKBase, SKBranch, ClientType, SKStatus, GFCID, GFPID, Account_Open_Date, Account_Update FROM ClientsAccounts_IMPORT) AS ccai ON cca.Branch_Account = ccai.ClientAccount Table definitions follow: CREATE TABLE [dbo].[ExistingClientsAccounts_IMPORT]( [AccountID] [int] NOT NULL, [SKBranch] [varchar](2) NOT NULL, [SKAccount] [varchar](12) NOT NULL, [SKName] [varchar](255) NULL, [SKBase] [varchar](16) NULL, [SyncStatus] [varchar](50) NULL, [SKCCY] [varchar](5) NULL, [ClientType] [varchar](50) NULL, [GFCID] [varchar](10) NULL, [GFPID] [varchar](10) NULL, [SyncInput] [smalldatetime] NULL, [SyncUpdate] [smalldatetime] NULL, [LastUpdatedBy] [varchar](50) NOT NULL, [Deleted] [tinyint] NOT NULL, [Branch_Account] [varchar](16) NOT NULL, [AccountTypeID] [int] NOT NULL ) ON [PRIMARY] CREATE TABLE [dbo].[ClientsAccounts_IMPORT]( [NEWClientIndex] [bigint] NOT NULL, [ClientGroup] [varchar](255) NOT NULL, [ClientAccount] [varchar](255) NOT NULL, [SKAccount] [varchar](255) NOT NULL, [SKDesc] [varchar](255) NOT NULL, [SKBase] [varchar](10) NULL, [SKBranch] [varchar](2) NOT NULL, [ClientType] [varchar](255) NOT NULL, [SKStatus] [varchar](255) NOT NULL, [GFCID] [varchar](255) NULL, [GFPID] [varchar](255) NULL, [Account_Open_Date] [smalldatetime] NULL, [Account_Update] [smalldatetime] NULL, [SKType] [varchar](255) NOT NULL ) ON [PRIMARY] The error message I get is: Msg 8152, Level 16, State 14, Line 1 String or binary data would be truncated. The statement has been terminated.

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  • Join two tables with same # of row but sorted for NULL

    - by VISQL
    I need to join two tables with the same number of rows. Each table has 1 column. There is NO CONNECTING COLUMN to reference for a join. I need to join them side by side because each table was sorted separately so that numeric values are at the top in descinding order. The Table Earners has income values from say 200K down to 0. I cannot just select using 2 cases, because then I will have my first row with Incomes above 100K, but the first 20 or so entries in the second row are NULL. I want the second row to also be sorted descending. I looked up using ORDER BY within CASE but there is no such thing. I have tried to read about row_number() but none of the examples seem to match or make sense. drop table #20plus select case when Income >= 20000 AND Income < 100000 then Income end as 'mula' into #20plus from Earners order by mula desc drop table #100plus select case when Income >= 100000 then Income end as 'dinero' into #100plus from Earners order by dinero desc Select A.dinero, B.mula FROM #100plus as A JOIN #20plus as B ON A.????? = B.????? Since both A and B are sorted descending, moving all NULL to the bottom, what can I reference to join the two tables? Previous output using one SELECT statement with 2 CASE statements dinero mula 2.12688e+007 NULL 1.80031e+007 NULL 1.92415e+006 NULL … … NULL 93530.7 NULL 91000 NULL 84500 Desired output using one SELECT statement after creating two temp TABLES dinero mula 2.12688e+007 93530.7 1.80031e+007 91000 1.92415e+006 84500 … 82500 NULL 82000 NULL … NULL NULL This is Microsoft SQL Server 2008. I'm super new to this, so please give an answer as clear and simplified as possible. Thank you.

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  • Behavior of <- NULL on lists versus data.frames for removing data

    - by Ananda Mahto
    Many R users eventually figure out lots of ways to remove elements from their data. One way is to use NULL, particularly when you want to do something like drop a column from a data.frame or drop an element from a list. Eventually, a user comes across a situation where they want to drop several columns from a data.frame at once, and they hit upon <- list(NULL) as the solution (since using <- NULL will result in an error). A data.frame is a special type of list, so it wouldn't be too tough to imagine that the approaches for removing items from a list should be the same as removing columns from a data.frame. However, they produce different results, as can be seen in the example below. ## Make some small data--two data.frames and two lists cars1 <- cars2 <- head(mtcars)[1:4] cars3 <- cars4 <- as.list(cars2) ## Demonstration that the `list(NULL)` approach works cars1[c("mpg", "cyl")] <- list(NULL) cars1 # disp hp # Mazda RX4 160 110 # Mazda RX4 Wag 160 110 # Datsun 710 108 93 # Hornet 4 Drive 258 110 # Hornet Sportabout 360 175 # Valiant 225 105 ## Demonstration that simply using `NULL` does not work cars2[c("mpg", "cyl")] <- NULL # Error in `[<-.data.frame`(`*tmp*`, c("mpg", "cyl"), value = NULL) : # replacement has 0 items, need 12 Switch to applying the same concept to a list, and compare the difference in behavior. ## Does not fully drop the items, but sets them to `NULL` cars3[c("mpg", "cyl")] <- list(NULL) # $mpg # NULL # # $cyl # NULL # # $disp # [1] 160 160 108 258 360 225 # # $hp # [1] 110 110 93 110 175 105 ## *Does* drop the `list` items while this would ## have produced an error with a `data.frame` cars4[c("mpg", "cyl")] <- NULL # $disp # [1] 160 160 108 258 360 225 # # $hp # [1] 110 110 93 110 175 105 The main questions I have are, if a data.frame is a list, why does it behave so differently in this scenario? Is there a foolproof way of knowing when an element will be dropped, when it will produce an error, and when it will simply be given a NULL value? Or do we depend on trial-and-error for this?

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  • Are null references really a bad thing?

    - by Tim Goodman
    I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of the language can be a source of errors if used improperly. And what's the alternative? I suppose instead of saying this: Customer c = Customer.GetByLastName("Goodman"); // returns null if not found if (c != null) { Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } You could say this: if (Customer.ExistsWithLastName("Goodman")) { Customer c = Customer.GetByLastName("Goodman") // throws error if not found Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } But how is that better? Either way, if you forget to check that the customer exists, you get an exception. I suppose that a CustomerNotFoundException is a bit easier to debug than a NullReferenceException by virtue of being more descriptive. Is that all there is to it?

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  • Issue with TagBuilder.MergeAttribute for parameter null

    - by The Yur
    I would like to use Razor's feature not to produce attribute output inside a tag in case when attribute's value is null. So when Razor meets <div class="@var" where @var is null, the output will be mere <div. I've created some Html extension method to write text inside tag. The method takes header text, level (h1..h6), and html attributes as simple object. The code is: public static MvcHtmlString WriteHeader(this HtmlHelper html, string s, int? hLevel = 1, object htmlAttributes = null) { if ((hLevel == null) || (hLevel < 1 || hLevel > 4) || (s.IsNullOrWhiteSpace())) return new MvcHtmlString(""); string cssClass = null, cssId = null, cssStyle = null; if (htmlAttributes != null) { var T = htmlAttributes.GetType(); var propInfo = T.GetProperty("class"); var o = propInfo.GetValue(htmlAttributes); cssClass = o.ToString().IsNullOrWhiteSpace() ? null : o.ToString(); propInfo = T.GetProperty("id"); o = propInfo.GetValue(htmlAttributes); cssId = o.ToString().IsNullOrWhiteSpace() ? null : o.ToString(); propInfo = T.GetProperty("style"); o = propInfo.GetValue(htmlAttributes); cssStyle = o.ToString().IsNullOrWhiteSpace() ? null : o.ToString(); } var hTag = new TagBuilder("h" + hLevel); hTag.MergeAttribute("id", cssId); hTag.MergeAttribute("class", cssClass); hTag.MergeAttribute("style", cssStyle); hTag.InnerHtml = s; return new MvcHtmlString(hTag.ToString()); } I found that in spite of null values for "class" and "style" attributes TagBuilder still puts them as empty strings, like <h1 class="" style="" But for id attribute it surprisingly works, so when id's value is null, there is no id attribute in tag. My question - is such behavior something that should actually happen? How can I achieve absent attributes with null values using TagBuilder? I tried this in VS2013, MVC 5.

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