Look at the following code. Are they the same? Is there any difference? If yes what?      string f = textBox5.Text;     if (string.IsNullOrEmpty(f))     {         MessageBox.Show("string");     }     if (String.IsNullOrEmpty(f))     {         MessageBox.Show("String");     }   Edit: Is a null or empty string test exactly the same as null or empty String test?
Example (note the case):  string s = "Hello world!"; String s = "Hello world!";   What are the guidelines for the use of each? And what are the differences?
workspace switching via ctrl + alt + arrow not working after upgrade to 13.04, how to fix this? What "time travel" story required the traveller to mentally reconstruct his world in order to return to it? Here's what I remember about it:   The protagonist is sent a relatively short distance into the future (maybe a year? I've forgotten). When he arrives in this "future" he finds himself in a completely different world, with non-human inhabitants. The inhabitants use a machine to teach him their torturous language. He tries to return home, and (eventually) finds himself in a realm of chaos/nothingness. He laboriously reconstructs in his mind everything he can remember about his home and finds himself back there somehow. The twist is      that in his "home" reality everyone speaks the language he was taught by the non-human inhabitants at his first stop. Is there a word to describe someone who tends to disagree with others only to upset them? I want to show that for $S,T\in B(H)$ bounded operators on Hilbertspace with $S\geq 0,T\geq 0$ and $ST=TS$,  we have $S+T\geq 0$, and $ST\geq 0$.  $T\geq 0$ means $(Tx,x)\geq 0$.    To me it seems that $((S+T)x,x) = (Sx,x)+(Tx,x)\geq 0$. But for $ST$ i like some help.   There is a theorem in Rudin (12.32) that says that for every $T\in B(H)$ we have an equivalence:   $T$ is positive $\Leftrightarrow$ $T$ is self adjoint, i.e. $T=T^*$ and $\sigma(T)\subset [0,\infty)$.   Since $S, T$ are self adjoint we know that $ST=TS = S^*T^* = T^*S^*$ ($ST$ is selfadjoint since $S,T$ commute). Also I read somewhere that if $S,T $ commute then $\sigma(ST)\subset \sigma(S)\sigma(T)$, but I am not sure if this is true. Clearly I cant prove it, but if it were true by this ''Theorem'' it would follow that $ST \geq 0$.   Is there a more straightforward way? ASP.NET Website's BIN directory and references File1:  .tid.setnr := 1123  .tid.setnr := 3345  .tid.setnr := 5431 .tid.setnr := 89323   File2:  .tid.info := 12 .tid.info := 3 .tid.info := 44 .tid.info := 60   Output file:  .tid.info := 12 .tid.setnr := 1123 .tid.info := 3 .tid.setnr := 3345 .tid.info := 44 .tid.setnr := 5431 .tid.info := 60 .tid.setnr := 89323 Is the Higgs boson an elementary particle? If so, why does it decay? The  is an excitation of the Higgs field and is very massive and short lived. It also interacts with the Higgs field and thus is able to experience mass.   Why does it decay if it is supposed to be an elementary particle according to the standard model? Is there an infinite amount of wavelengths of light? Is the EM spectrum continuous? The electromagnetic spectrum is a continuum of wavelengths of light, and we have labels for some ranges of these and numerical measurements for many.  Question: Is the EM spectrum continuous such that between two given wavelengths (e.g. 200nm and 201nm) there is an infinite number of distincts wavelengths of light?  Or is there some cut-off of precision with which light might exist (e.g. can light only have wavelengths of whole number when measured in nanometers, etc.)? Numbering side-by-side equations or inline equations Use chown to set the ownership of all a folder's subfolders and files? How can I use the chown command to change the ownership of all a folder's subfolders and files? Heisenberg famously derived his uncertainty principle by considering the disturbance that a measurement would have on a small enough system.  Of course in the mathematical formalism of Quantum Mechanics the relationship is derived from more basic principles.  How does String Theory account for it? Heuristically, and mathematically? Origin of electric charge I wonder is it legal to register a domain name that contains a company name. For example cococola.cc (considering that this domain name is available). Can I buy and use any domain names that contain a name of a trademark? How to prove $\hat{p}|x\rangle=i\hbar\frac{\partial}{\partial x}|x\rangle$,using $[\hat{x},\hat{p}]=i\hbar$? How to prove $$\hat{p}|x\rangle=i\hbar\frac{\partial}{\partial x}|x\rangle,$$ using $$[\hat{x},\hat{p}]=i\hbar~?$$ The question seems to be uncomplete because for any $f(x)$ $$[\hat{x},\hat{p}+f(x)]=i\hbar.$$ But that's my homework. Can someone add some appropriate assumptions and prove the question?  Here is a seemingly right answer:  $$ \hat{Q} = e^{-i \frac{u}{\hbar} \hat{p}},[\hat{x},\hat{Q}]=u \hat{Q} $$ $$ \hat{x}\hat{Q}|x\rangle = (x+u)\hat{Q}|x\rangle $$ $$ \hat{Q}|x\rangle = |x+u\rangle $$ $$ \hat{T} = e^{i \frac{u}{\hbar} \hat{x}},[\hat{p},\hat{T}]=u \hat{T} $$ $$ \hat{p}\hat{T}|p\rangle = (p+u)\hat{T}|p\rangle $$ $$ \hat{T}|p\rangle = |p+u\rangle $$  Therefore  $$ \langle x | p \rangle = e^{i\frac{px}{\hbar}} \langle 0 |_x |0 \rangle_p $$  $$ \delta(p-p') = \langle p | p' \rangle  = 2\pi \hbar |\langle 0 |_x |0 \rangle_p|^2 \delta(p-p') $$ $$ \langle 0 |_x |0 \rangle_p = \sqrt{\frac{1}{2 \pi \hbar}}$$ $$ \hat{p}|x\rangle = \int \hat{p} |p\rangle\langle p |x\rangle= \int \hat{p} |p\rangle e^{-i\frac{px}{\hbar}}\sqrt{\frac{1}{2 \pi \hbar}} = i\hbar\frac{\partial}{\partial x}|x\rangle $$ Which assumption is made here? How to install Eclipse? Javascript profanity match NOT replace I have a Python regular expression that contains a group which can occur zero or many times - but when I retrieve the list of groups afterwards, only the last one is present. Example:  re.search("(\w)*", "abcdefg").groups()  this returns the list ('g',)  I need it to return ('a','b','c','d','e','f','g',)  Is that possible? How can I do it? A blinding light / blinding sunlight / a blinding sunlight "Mornings came and cast a blinding sunlight over everything, and he felt like nothing worthwhile could be accomplished."  For some reason, I feel like "a blinding light" is ok, but if its sunlight, then I should drop the "a" and write "cast blinding sunlight", but I'm not sure why I feel this way.   Can anyone offer some enlightenment?  edit - alternate phrasing, closer to being a literal translation: "Mornings came without warning, flooding the day with a strong sun, and he felt like nothing worthwhile could be accomplished."   I would still like an answer to the technical question of whether I should drop the "a", but would also appreciate knowing if anyone thinks option #2 is a better choice. Is there a more accurate way to create a Javascript timer than setTimeout? Just received ~70 unsolicited password reset mails from Super User, so abusive...