variable-assignment

Consider the following 2 scenarios: boolean b = false; int i = 0; while(i++ < 5) { b = true; } OR boolean b = false; int i = 0; while(i++ < 5) { if(!b) { b = true; } } Which is more "costly" to do? If the answer depends on used language/compiler, please provide. My main programming language is Java. Please do not ask questions like why would I want to do either.. They're just barebone examples that point out the relevant: should a variable be set the same value in a loop over and over again or should it be tested on every loop that it holds a value needed to change? Please do not forget the

I am a RoR programmer new to Python. I am trying to find the syntax that will allow me to set a variable to a specific value only if it wasn't previously assigned. Basically I want: # only if var1 has not been previously assigned var1 = 4 This is a very different style of programming, but I always try to rewrite things that looked like bar = None if foo(): bar = "Baz" if bar is None: bar = "Quux" into just: if foo(): bar = "Baz" else: bar = "Quux" That is to say, I try hard to avoid a situation where some code paths define variables but others don't. In my code, there is never a path which

The new destructuring assignment features of ES6 are fairly well known now ( live copy on Babel's REPL); in the case of variables that already exist: let a, b; // Existing variables let o = {a: "a", b: "b"}; // An object to get values from // ... ({a, b} = o); // Set them to the props from `o` console.log(a); // "a" console.log(b); // "b" Is there a simple converse in ES6? Setting properties on an existing object based on variables with the same name? (Other than the obvious o.a = a; o.b = b; ) Note I'm not talking about when creating an object, we could do that with the wonderful new object

This question already has an answer here: Multiple assignment in javascript? What does [a,b,c] = [1, 2, 3]; mean? 4 answers var a,b,c; var arr = [1,2,3]; [a,b,c] = arr; this code works perfectly in Firefox resulting a=1, b=2 and c=3, but it doesn't work in Chrome. Is it a Chrome bug or it is not valid javascript code? (I failed to find it in javascript references) How can I modify this code to make it suitable for Chrome, with minimum damage to it? (I don't really like to write a = arr[0]; b = arr[1]... or the same with arr.shift() all the time) P.S. this is just an example code, in real code

(Don't worry, this isn't another question about unpacking tuples.) In python, a statement like foo = bar = baz = 5 assigns the variables foo, bar, and baz to 5. It assigns these variables from left to right, as can be proved by nastier examples like >>> foo[0] = foo = [0] Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'foo' is not defined >>> foo = foo[0] = [0] >>> foo [[...]] >>> foo[0] [[...]] >>> foo is foo[0] True But the python language reference states that assignment statements have the form (target_list "=")+ (expression_list | yield_expression)

I have here char text[60]; Then I do in an if : if(number == 2) text = "awesome"; else text = "you fail"; and it always said expression must be a modifiable L-value. You cannot change the value of text since it is an array, not a pointer. Either declare it as char pointer (in this case it's better to declare it as const char* ): const char *text; if(number == 2) text = "awesome"; else text = "you fail"; Or use strcpy: char text[60]; if(number == 2) strcpy(text, "awesome"); else strcpy(text, "you fail"); 来源： https://stackoverflow.com/questions/6008733/expression-must-be-a-modifiable-l-value