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error: ‘NULL’ was not declared in this scope

I get this message when compiling C++ on gcc 4.3 error: ‘NULL’ was not declared in this scope It appears and disappears and I don't know why. Why? Thanks. ...

What does i:nil="true" mean?

I have an xml and it has nodes with i:nil="true" in it. What does that mean? For example: <FirstName i:nil="true" /> Does that mean something different than: <FirstName /> If so, what is the difference? ...

Use reflection to set a property value to Nothing (Null)

Edit: Based on the answer from LoveMeSomeCode, I believe this issue only appears in VB.Net. I'm trying to revert a class to a previous state by saving the old values of changed properties in a dictionary and setting them via reflection when I need to revert. I'm having a problem where if the old value is Nothing (null) I get a null refe...

Does it help GC to null local variables in Java

I was 'forced' to add myLocalVar = null; statement into finally clause just before leaving method. Reason is to help GC. I was told I will get SMS's during night when server crashes next time, so I better did it :-). I think this is pointless, as myLocalVar is scoped to method, and will be 'lost' as soon as method exits. Extra nulling j...

SQL 'Or' operator. How does it work in the following scenario?

I've been working on optimizing a query and have ran into a situation that's making me question how I've always used SQL's OR operator. (SQL Server 2000 also) I have a query where the conditional (WHERE) clause looks something like this: WHERE (Column1 = @Param1 or Column1 LIKE @Param1 + '%') AND (@Param2 = '' OR Column2 = @Param2 OR C...

How to check null objects in jQuery

I am using jQuery, I want to check existence of an element in my page. I have done following code, but its not working? if ($("#btext" + i) != null){ //alert($("#btext" + i).text()); $("#btext" + i).text("Branch " + i); } Please tell me what will be the right code? Thanks ...

How to simplify a null-safe compareTo() implementation?

I'm implementing compareTo() method for a simple class such as this (to be able to use Collections.sort() and other goodies offered by the Java platform): public class Metadata implements Comparable<Metadata> { private String name; private String value; // Imagine basic constructor and accessors here // Irrelevant parts omitted...

How can I test an NSString for being nil?

Can I simply use if(myString == nil) For some reason a string that I know is null, is failing this statement. ...

How can I send a NULL in Ruby Sockets?

I'm working on a socket app in Ruby Shoes, and want to send a message to the server. The server expects the XML message, and then a null (0) character. How can I send that in TCP Sockets in Ruby? Thanks. ...

Webbrowser control's window.external is ALWAYS null

The Web browser's Window.External object is always null! To reproduce drop a web browser on a new winform and type: Option Strict Off Public Class Form1 Private Sub Form1_Load() Handles MyBase.LoadMe.WebBrowser1.Document.Window.DomWindow.External.AddFavorite("http://www.google.com") End Sub End Class Make certain you...

MEF: Unable to import in other classes?

Edit: Matt, that does indeed solves some (most) of my problems, thank you. Now the only lingering issue of how do I do this in WPF? I have a custom part based off of a UserControl but there is no way in WPF to do : [Import]<my:SomeCustomControl> so the cascade doesn't work in this instance. /Edit I am having an issue [Import]ing...

How do I use GNU Screen transparently

I want to use GNU screen in such a way that the user doesn't know it's there. It's to help ensure that a text based management application that I'm writing can only be used by a single user at a time. To guard against against users locking everyone else out by running the application and going, leaving it running when going on holiday, I...

Why are null char disallowed even in CDATA sections?

XML, Why are null char disallowed even in CDATA sections? It seems to terminate the file right there. Any solution? Base64? ...

Precedence of C# ?? operator

Hi, I've just tried the following, the idea being to concatenate the two strings, substituting an empty string for nulls. string a="Hello"; string b=" World"; -- Debug (amusing that ? is print, doesn't exactly help readability...) ? a ?? "" + b ?? "" -> "Hello" Correct is: ? (a??"")+(b??"") "Hello World" I was kind of expe...

Linq2SQL: Always get .Sum() to return 0 instead of null

Is there any way (through a extention mechanism?) to get the Sum() function to allways return 0. My workaround now is to write like this, but I'm hoping there's a better solution? ((int?)e.CampaignCodes.Sum(f => f.Enquiries.Count()) ?? 0), ...

Testing a C# Function Pointer (Delegate) for Null

I am testing a function pointer called ErrorLoggingMethod in a C# DLL to prevent exceptions due to a null value, as below, but it seems that at runtime, the function is actually being executed when I really mean to test its delegate for null. I am inadvertently getting a null exception as a result--just what I am trying to avoid! My or...

Testing pointers for validity (C/C++)

Is there any way to determine (programatically, of course) if a given pointer is "valid"? Checking for NULL is easy, but what about things like 0x00001234? When trying to dereference this kind of pointer an exception/crash occurs. A cross-platform method is preferred, but platform-specific (for Windows and Linux) is also ok. Update for...

Space used by nulls in database

If a column is null, does that affect the space used by the column? Is the space used fixed by the column definition? Does this vary from database to database. (I am mainly interestred in SQL Server 2000.) Clarification: The question relates not to what happens when the column is 'nullable' (This costs another bit as Kritsen & gbn point...

NULL vs nil in Objective-C

In observeValueForKeyPath:ofObject:change:context: - why do the docs use NULL instead of nil when not specifying a context pointer? ...

Is it possible to return a NULL value over Response.Write?

context.Response.ContentType = "text/plain"; context.Response.Write(returnString); If returnString is NULL what will it pass, or will it fail? EDIT: The question was if it is possible, the above was just an example which I realize I could have tested. However I am looking for any other possible ways to do this beyond just my code exam...