How to fix Null Reference Exception occurred between two classes?
What is a NullReferenceException, and how do I fix it?
Illustrator CS5 brick pattern with perspective I created a curving arrow shape that starts wide at the bottom and thins out near the top where the point is. I also created a brick pattern swatch but when I apply it to the shape it appears like the pattern is overlaid instead of like a real road where the bricks follow the shape and narrows near the most distant point. How can I apply a perspective to the brick pattern without looking like I used a clipping mask?  Here is a link to what I achieved with a clipping mask - not what I want though. I need the bricks to look like they are inlaid just like in real life. Playing a video in full screen after startup DNS Resolution for example.com - Can you explain? Showing a compact metric space has a countable dense subset Old post apocalyptic cartoon where the main character has red hair and lives with a nomadic group I am looking for an animated TV series which was probably made in the '80s or '90s.  The main character had red hair.  The cartoon is set in a post apocalyptic environment and the character lives with his mother and an old man —his mentor I guess— with a nomadic group.  In one early episode, one of the group is wounded in an ambush, he is taken back to the camp where the mentor performs surgery which is revealed he learned during the war. The wound is caused by a bullet, then the mentor is surprised saying that guns were lost and forgotten.  In another episode the main character is captured and sent to a prison. Then after he escapes with other prisoners, they look outside the gate and see grass and soil which they either didn't see in their lives or were in the prison for a long time.  The main character later finds a sword like Excalibur which can cause some sort of electrical disruptions.  I think his mother was kidnapped in the beginning. Convert all text from uppercase to lowercase and vice versa? My question is how can I convert all text from uppercase to lowercase and vice versa? That is to change the cases of all the letters. It has to be done with a sed replacement somehow. Possible bug in sidebar "question asked:" date Show that an algebraically closed field must be infinite.    Answer  If F is a finite field with elements $a_1, ... , a_n$ the polynomial $f(X)=1 + \prod_{i=1}^n (X - a_i)$ has no root in F, so F cannot be algebraically closed.  My Question  Could we not use the same argument if F was countably infinite? Couldn't we say that if F was a field with elements $a_1, a_2, ... $ then the polynomial $f(X) = 1 + \prod_{i=1}^{\infty} (X - a_i)$ does not split over F?  Thank you in advance Is it possible to view Google Chrome bookmarks and history from the terminal Is it possible to view Google Chrome bookmarks and history by using command line? I have a header file  x.h which is included by more than one *.c source files. This header file has some structure variables defined.  I have put multiple inclusion prevention guard at the beginning of the header file as:  #ifndef X_H #define X_H ... .. //header file declarations and definitons.   #endif//X_H   On building I get linker errors related to multiple definitions. I understand the problem.   Won't a multiple inclusion prevention guard at the top of header file as I have, prevent multiple inclusions of the header file x.h and thereby avoid multiple definitions of the variables that are there in x.h? #pragma once does not work on this particular compiler, so what is the solution?  Someone had posted  answer to a similar question. It doesn't seem to work for me. How does this solution work? How can I show that $(n-1)!\equiv-1 \pmod{n}$ if and only if $n$ is prime? Thanks. Calculus book recommendations (for complete beginner) Well I have not started calculus yet but I am really keen to. I would love if you suggest some books.  Points to be noted:   I really don't like the way textbooks are written so please no "textbooks"  I am COMPLETELY beginner in calculus. I know a little bit of trigonometry and what functions are but not really in depth.The book should start from the base, I mean really from the base. I may require a precalculus book too if the books don't cover that. I would really love if the book shows how calculus was developed, why it was developed and things like that.   Well,thanks in advance! Does C# have anything comparable to Python's list comprehensions? How to assign permanent drive letters to removable USB hard drives I have scripts that expect specific drive letters for hard drives. Windows sometimes assigns the different drive letters (e.g. I expected my Maxtor drive to be E:, but it's now F:, therefore my scripts will fail), depending on the order of how the drives are plugged into my laptop.  In Windows 7, how do I assign a permanent drive letter to a drive? Any way to do DISTINCT ON? I'm trying to create a query like this:  SELECT DISTINCT ON (field1, field2) field1, field2, field3 FROM table1   But can't figure out how to get DISTINCT ON narrowed down to a few fields in Drupal like that. Calling $query-&gt;distinct() just seems to structure the query like this:  SELECT DISTINCT field1, field2, field3 FROM table1   I did figure out a hacky way to add what I want by adding an expression before I add any fields like this:  $query-&gt;addExpression('DISTINCT ON (field1, field2) field1', 'field1');   Which creates:  SELECT DISTINCT ON (field1, field2) field1 as field1, field2, field3 FROM table1   I'm looking for a better way to this ? I have a normal door, and left to its own devices it will simply rest about 20-30 degrees. It won't swing shut on its own, nor stay open on its own. It hangs a bit in the middle. Convenient enough to catch you elbow when you're not looking.  I'd like the door to stay put wherever we leave it.  I've heard idea such as slipping cardboard in to the hinge to rebalance the door, etc. but no guidelines as to the thickness of that cardboard, or which hinge to change to move it in which direction.  I would hope you can appreciate how I'd rather not make this a task of trial and error and continually removing the hinge and putting it back on, etc.  I've also heard something about lightly bending one of the hinge pins, but not sure how I should go about that, or "how much" to bend it.  So, I'm looking for some tips on how to fix this (and other) door. I am using Eclipse 3.3 ("Europa"). Periodically, Eclipse takes an inordinately long time (perhaps forever) to start up. The only thing I can see in the Eclipse log is:       !ENTRY org.eclipse.core.resources 2 10035 2008-10-16 09:47:34.801     !MESSAGE The workspace exited with unsaved changes in the previous session; refreshing workspace to recover changes.   Googling reveals  that I remove the folder:  workspace\.metadata\.plugins\org.eclipse.core.resources\.root\.indexes   This does not appear to have helped.  Short of starting with a new workspace (something which I am not keen to do, as it takes me hours to set up all my projects again properly), is there a way to make Eclipse start up properly? Is the XP for an encounter split among the party members or not? At this point, I am unclear as to how to handle encounter XP. Does each surviving party member receive a proportional share, or the full amount? That is, assume a 4-character party had completed an encounter worth 400 XP. Would each party member receive 100 XP, or 400 XP? There is a problem with my logic and I cannot seem to point out where. There's a rocket ship travelling at close-to-c speed v without any acceleration (hypothetically), and there is an observer AA with a clock A on Earth, and there's another observer on the rocket BB with a clock B and these two clocks were initially in sync when the rocket was at rest with a FoR (frame of reference) attached to Earth. Now, this rocket's moving and AA tells us that B is running slower than A by a factor of$$ \gamma = 1 /(1-v^2/c^2)^{1/2} $$ $$ t_A/t_B = \gamma $$ where v is the relative 1d- velocity between the two i.e the earth and the rocket! That would mean the time elapsed on A is greater than that on B but this will happen only in the FoR of AA? So $t_B$ in this equation must be the time on B as observed by AA? Is this correct? What do the terms mean in the equations? If the symmetry holds and BB doesn't accelerate, then BB could say that $$ t_B/t_A = \gamma $$ right? where $t_B$ and $t_A$ are the times on B and A with respect to FoR of BB? But I was solving this problem and I took the earth FoR of A, but the prof took the rocket FoR of B? Like how will I know which FoR to solve the problem from? It'd greatly help if the terms in all the above equations were laid down neatly! DO we even need these FoRs?? Because in all the solved problems the prof is't specifying any and is using random ones! Please help!!!! This is the question where I messed up. The first rocket bound for Alpha Centauri leaves Earth at a velocity (3/5)c. To commemorate the ten year anniversary of the launch, the nations of Earth hold a grand celebration in which they shoot a powerful laser, shaped like a peace sign, toward the ship.  According to Earth clocks, how long after the launch (of the rocket) does the rocket crew first see the celebratory laser light?  This must be 25 years. My reasoning is: If v = 3c/5 10v + vt = ct where t is time taken by the light to reach the rocket from Earth as calculated from Earth.. and I solved that for t. and added 10 years to that because the time starts at the launch of the rocket!  According to clocks on the rocket, how long after the launch does the rocket crew first see the celebratory laser light?  This is 20 years. Here, I say: If it takes 25 years as observed by clocks on earth for the laser to reach the rocket, what should be the corresponding time as seen on a clock on the rocket? Using the formula: 25 = $\gamma$t where $\gamma$= 5/4 solved for t!  According to the rocket crew, how many years had elapsed on the rocket's clocks when the nations of Earth held the celebration? That is, based on the rocket crews' post-processing to determine when the events responsible for their observations took place, how many years have passed on the rocket's clocks when the nations of Earth hold the celebration?  For this, I did the following: 10 years on earth = T years on rocket ship where T must be lesser than 10 as observed from Earth FoR! Therefore, T= 4(10)/5 years = 8 years! But, prof says, 10 years on Earth = T years in rocket ship where T must be GREATER than 10 as observed from the rocket FoR??? Therefore, T = 10(5/4) years = 12.5 years!! What does this question actually want? Remove completed reminders in OS X and iOS