I'm writing a plug-in for a geometric modeling program, and I have an abstract class that is based off a Curve object. The curve is only considered valid if it is planar, closed, and does not intersect itself. I then have a chain of other methods that reference this curve that do things like make a surface out of it, or extrude it into...
Hello, I realize that the exact question has been asked before on stack overflow with only a vaguely conclusive answer: link So here it is again. Table A: Has an integer column which is nullable, along with an index. Query: SELECT * from table WHERE column IS null LIMIT 10; Will an index be used, or will mysql do a full table scan un...
I have some String variables which are getting the values from invoking the function getParameter() and some of this variables will probably be null. Later, I will evaluate this variables using equals() method. Should I set all the String variables to the empty String ("") if they are null to avoid any problems? ...
Hey guys, hoping for some help with this :( been stuck on it for a couple days now. I'm creating a ScrollBar using Lee Brimelow's ScrollBar class. I've had to modify it to work inside of my Class files and think I'm on the right track, but I'm getting the dreaded: Error #1009: Cannot access a property or method of a null object refere...
Is there a way to prevent a treemap from accepting null values, or do I need to do a check every time I enter something? ...
I just started playing with MVC and I've run into a roadblock. I'm using a partial view as a User Login flyout on the header of each page using OpenID. When the user clicks on the provider (similar to stackoverflow) it authenticates and then either returns to the calling page or redirects to the signup page. The code works flawlessly ...
I'm confused why the following C++ code can compile. Why does a call to delete the method of 0 not produce any error?! volatile *arr = NULL; // or if i use 0, it's the same thing delete arr; I did try to run it, and it did not give me any error at all... ...
I have been using javascript for couple of years and never cared about the difference between null & undefined earlier, i always use undefined to validate the object existence. But recently i came through this article. Here they said JavaScript distinguishes between null, which is an object of type 'object' that indicates a del...
This is a sample code: NSDictionary *myDictionary = [NSDictionary dictionary]; NSNumber *myNumber = [myDictionary valueForKey: @"MyNumber"]; NSLog(@"myNumber = %@", myNumber); // output myNumber = (null) if (myNumber == nil) NSLog(@"test 1 myNumber == nil"); if (myNumber == NULL) NSLog(@"test 2 myNumber == NULL"); if ([myN...
I want to know which is the preferred way to declare a string in C#: string strEmpty = String.Empty; or string strNull = null; Which practice is better or what is the difference between these statements. ...
Hi, My requirement is to display a Column in select query when a condition satisfies and not to display the column when condition is not matched. For eg : In this simple table below Table : XYZ Name ID Fairness harish 3 White ravi 5 brown arun 2 black rahul 5 white Query: select name,case id when 5 then " I Like to learn more...
Background Let's say I have the following class: public class MyValue<T> { public T Value { get; set; } public static bool operator ==(MyValue<T> first, MyValue<T> second) { // if first and second are the same instance, they are equal if (object.Equals(first, second)) { return true; ...
Here is the below Code: $query = mysql_query("SELECT * FROM tablex"); if ($result = mysql_fetch_array($query)){ if ($result['column'] == NULL) { print "<input type='checkbox' />"; } else { print "<input type='checkbox' checked />"; } } If the values are NOT NULL i still get the uncheked box. Am i doing something wrong from a...
The CLR Profiler can also reveal which methods allocate more storage than you expected, and can uncover cases where you inadvertently keep references to useless object graphs that otherwise could be reclaimed by GC. (A common problem design pattern is a software cache or lookup table of items that are no longer needed or are safe to r...
I have noticed that when I was running Windows XP, if my code dereferenced null I would get a crash in debug and I could then easily identify where the bug was coming from. It seems that in Windows 7 (I'm running 64-bit), instead of crashing or creating any sort of notification, the code will simply break its current iteration and start...
Hi, I'm having a document.body is null error in my javascript because I use: $(window).width() as value to assign to a variable in my $(document).ready(function(){}); I would be very grateful to anyone who could help me with this. Kind regards edit: sorry if this all was unclear. I have a demo at: http://www.wpmonk.com/demo/...
In the following code, what is the benefit of using (!!p) instead of (p != NULL)? AClass *p = getInstanceOfAClass(); if( !!p ) // do something else // do something without having valid pointer ...
I have an expression tree class, which has a method buildExpressionTreeFromQueue. As its name suggests, the method takes a queue (just a series of operators and operands) and cycles through it, adding nodes to the tree appropriately. My problem is this: when I try to write the tree as Infix notation (or Prefix or Postfix for that matter...
Maybe my memory has gone completely wacko, but I think I remember that declaring pointers without initializing them made them point to nil. But recently this doesn't seem to be the case. Has it always been this way? Or has it something to do with the compiler settings? ...
[ This is a result of Best Practice: Should functions return null or an empty object? but I'm trying to be very general. ] In a lot of legacy (um...production) C++ code that I've seen, there is a tendency to write a lot of NULL (or similar) checks to test pointers. Many of these get added near the end of a release cycle when adding a N...