For classes, the == operator uses reference equality. Of course, structs are value types, so they can’t be compared by reference. There is no default implementation of == for structs because memberwise comparison isn’t always a valid comparison, depending on the type. You can instead use the Object.Equals method, which does compare memberwise: Console.WriteLine(user.Equals(default(User)) ? … Read more
The dot itself is not an operator, .^ is. The .^ is a pointwise¹ (i.e. element-wise) power, as .* is the pointwise product. .^ Array power. A.^B is the matrix with elements A(i,j) to the B(i,j) power. The sizes of A and B must be the same or be compatible. C.f. “Array vs. Matrix Operations”: … Read more
The technically correct answer is: because no one has written impl Add<f64> for i32 {}. The cheeky answer is: because Rust doesn’t want you to shoot yourself in the foot. The longer, potentially more useful answer is… In computers, integers and floating point numbers both have a limited range, ultimately driven by the number of … Read more
According to the LESS CSS website, you need to change the order of your equation The output is pretty much what you expect—LESS understands the difference between colors and units. If a unit is used in an operation, like in: @var: 1px + 5; LESS will use that unit for the final output—6px in this … Read more
The assignment expression a = b is not an lvalue in C, but it is in C++: C11, 6.5.14 (Assignment operators): An assignment operator stores a value in the object designated by the left operand. An assignment expression has the value of the left operand after the assignment, but is not an lvalue. C++14, 5.18 … Read more
Your problem stems from a misunderstanding of the or operator that is common to people learning programming languages like this. Yes, your immediate problem can be solved by writing x ~= 0 and x ~= 1, but I’ll go into a little more detail about why your attempted solution doesn’t work. When you read x … Read more
Look at this statement: x += x–; This is equivalent to: x = x + x–; Which is equivalent to: int a1 = x; // a1 = 10, x = 10 int a2 = x–; // a2 = 10, x = 9 x = a1 + a2; // x = 20 So x is 20 … Read more
You are wrong. There is no guarantee that ++ is atomic and neither is there for the compound assignment operators, or indeed for any C++ operation.
Referential Equality Java In Java, the default implementation of equals compares the variable’s reference, which is what == always does: The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and … Read more
You are trying to micro-optimize here, and that’s generally a big no-no. Unless you have performance analytics which are showing you that this is an issue, it’s not even worth changing. For general use, the correct answer is whatever is easier to maintain. For the hell of it though, the IL for the null coalescing … Read more