variable-assignment

Since a copy constructor MyClass(const MyClass&); and an = operator overload MyClass& operator = (const MyClass&); have pretty much the same code, the same parameter, and only differ on the return, is it possible to have a common function for them both to use? CB Bailey Yes. There are two common options. One - which is generally discouraged - is to call the operator= from the copy constructor explicitly: MyClass(const MyClass& other) { operator=(other); } However, providing a good operator= is a challenge when it comes to dealing with the old state and issues arising from self assignment. Also

Given this snippet of JavaScript... var a; var b = null; var c = undefined; var d = 4; var e = 'five'; var f = a || b || c || d || e; alert(f); // 4 Can someone please explain to me what this technique is called (my best guess is in the title of this question!)? And how/why it works exactly? My understanding is that variable f will be assigned the nearest value (from left to right) of the first variable that has a value that isn't either null or undefined, but I've not managed to find much reference material about this technique and have seen it used a lot. Also, is this technique specific to

I see at many places the use of slice assignment for list s. I am able to understand its use when used with (non-default) indices, but I am not able to understand its use like: a_list[:] = ['foo', 'bar'] How is that different from a_list = ['foo', 'bar'] ? a_list = ['foo', 'bar'] Creates a new list in memory and points the name a_list at it. It is irrelevant what a_list pointed at before. a_list[:] = ['foo', 'bar'] Calls the __setitem__ method of the a_list object with a slice as the index, and a new list created in memory as the value. __setitem__ evaluates the slice to figure out what

In many languages assignments are legal in conditions. I never understood the reason behind this. Why would you write: if (var1 = var2) { ... } instead of: var1 = var2; if (var1) { ... } It's more useful for loops than if statements. while( var = GetNext() ) { ...do something with var } Which would otherwise have to be written var = GetNext(); while( var ) { ...do something var = GetNext(); } I find it most useful in chains of actions which often involve error detection, etc. if ((rc = first_check(arg1, arg2)) != 0) { report error based on rc } else if ((rc = second_check(arg2, arg3)) != 0) {

I want to assign multiple variables in a single line in R. Is it possible to do something like this? values # initialize some vector of values (a, b) = values[c(2,4)] # assign a and b to values at 2 and 4 indices of 'values' Typically I want to assign about 5-6 variables in a single line, instead of having multiple lines. Is there an alternative? There is a great answer on the Struggling Through Problems Blog This is taken from there, with very minor modifications. USING THE FOLLOWING THREE FUNCTIONS (Plus one for allowing for lists of different sizes) # Generic form '%=%' = function(l, r, ...

I have the following code: public class Tests { public static void main(String[] args) throws Exception { int x = 0; while(x<3) { x = x++; System.out.println(x); } } } We know he should have writen just x++ or x=x+1 , but on x = x++ it should first attribute x to itself, and later increment it. Why does x continue with 0 as value? --update Here's the bytecode: public class Tests extends java.lang.Object{ public Tests(); Code: 0: aload_0 1: invokespecial #1; //Method java/lang/Object."<init>":()V 4: return public static void main(java.lang.String[]) throws java.lang.Exception; Code: 0: iconst_0