variable-assignment

Given the following code: a = true # let's assign `a` a value # and let's test if calling `b`, an unassigned variable, throws an error begin puts "The value of b is: #{b.inspect}" rescue NameError => e puts "Caught an error: #{e}" end a || b = true # the assignment should never be executed because `a` is `true` puts "The value of b is: #{b.inspect}" # will calling `b` still raise an error? We get the following result: Caught an error: undefined local variable or method `b' for main:Object The value of b is: nil Even though we expected calling b to raise an error the second time, we see that b

Possible Duplicate: C# variable initializations vs assignment Just like in the title, could someone please explain what is the difference between Initialization and Assignment in C#? I'm preparing for a test and I wanted to know what's the best way to answer this type of question. Thanks Cheers, n1te When you initialize a variable you're declaring it into existence. PlasticCup mySippyCup = new PlasticCup(); When you assign, you're just saying "this water" goes into "this cup". The cup already exists. mySippyCup = new PlasticCup(); Initialization is assigning value while declaring the variable

I recently stumbled across replace() and "[<-" . They seem to have similar functionality, for example with "[<-" I can do something like this: > x.tst <- array(1:6, c(2,3)) > s.tst <- array(0, c(2,3)) > s.tst [,1] [,2] [,3] [1,] 0 0 0 [2,] 0 0 0 > s.tst[1:3] <- 1 > "[<-"(x.tst, s.tst==1, 0) [,1] [,2] [,3] [1,] 0 0 5 [2,] 0 4 6 > x.tst [,1] [,2] [,3] [1,] 1 3 5 [2,] 2 4 6 Can somebody help to clarify the difference? What are the strengths of replace vs "[<-" and vis versa? They're basically exactly the same thing. If you look at the source code of replace, you'll see : function (x, list, values

I have always wondered why all apple code samples use code like this: UINavigationController *aNavigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController]; self.navigationController = aNavigationController; [self.view addSubview:[navigationController view]]; [aNavigationController release]; They always create a local variable and assign it to the ivar why don't they simply do this: self.navigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];; [self.view addSubview:[navigationController view]];

Python is all about writing beautiful code. So, I was running pylint to check the "beautifulness" of my code, when I bump into something: Unused variable 'myvar1' From this part of my code: for myvar1, myvar2 in mylist: # Do stuff just using myvar2 mylist is a list of tuples, so I'm unwrapping the tuples into two variables ( myvar1 and myvar2 ). I'm defining those two variables just to unwrap the second one, because I don't need the other. So, here's my question: Is there a way to tell the interpreter to unwrap the tuple, but not assing the first part (for example). In some other languages you

a,b = 0,1 while b < 50: print(b) a = b b = a+b outputs: 1 2 4 8 16 32 wheras: a,b = 0,1 while b < 50: print(b) a,b = b, a+b outputs (correct fibonacci sequence): 1 1 2 3 5 8 13 21 34 Aren't they the same? I mean a,b = b, a+b is essentially the same as a = b and b = a+b written separately -- no? No, they are not the same. When you write a,b = b, a+b , the assignments are done "simultaneously". a,b = b, a+b is same as (a, b) = (b, a+b) . So, after a, b = 5, 8 a=5 and b=8. When Python sees this (a, b) = (b, a+b) it first calculates the right side (b, a+b) which is (8,13) and then assigns (this