binary-operators

问题 I have this enum: public enum Operator { add("+", BigDecimal::add), subtract("-", BigDecimal::subtract), multiply("*", BigDecimal::multiply), divide("/", BigDecimal::divide), mod("%", BigDecimal::remainder); Operator(final String symbol, final BinaryOperator<BigDecimal> operation) { this.symbol = symbol; this.operation = operation; } public BinaryOperator<BigDecimal> getOperation() { return operation; } } I want to use the some MathContext , one can easily do that when performing an operation

问题 The Rust Reference presently says the following about the as operator: 7.2.12.5 Type cast expressions A type cast expression is denoted with the binary operator as . Executing an as expression casts the value on the left-hand side to the type on the right-hand side. An example of an as expression: fn average(values: &[f64]) -> f64 { let sum: f64 = sum(values); let size: f64 = len(values) as f64; sum / size } (Also, since it will be relevant: 7.2.12.8 Operator precedence The precedence of Rust

问题 I don't know how to convert a non terminating binary number(fraction) to decimal . Can anybody guide me how to do with an example? 回答1: if the binary number is a unterminated integer, it would be infinite (positive or negative). How can you represent infinite number in decimal? I think it's ∞ . else if the binary number is a float-point number, congratulations. In many standard of float-point number(e.g., IEEE 754), the mantissa is represented by a binary pattern in which the highest bit has

问题 I have this var json : [[String : Any]] = [[:]] which contains the JSON response as follows: { "id": "1", "name": "Apple", "category_name": "Fruits" }, { "id": "2", "name": "Black shirt", "category_name": "Fashion" }, { "id": "3", "name": "iPad", "category_name": "Gadgets" } And I wrote an enum: enum : Int { case fruits = 0, fashion, gadgets } var data = [Categories: [[String: Any]]]() Then I have this method to sort the categories: func sortData() { data[.fruits] = self.json.filter({ $0[

问题 I have this var json : [[String : Any]] = [[:]] which contains the JSON response as follows: { "id": "1", "name": "Apple", "category_name": "Fruits" }, { "id": "2", "name": "Black shirt", "category_name": "Fashion" }, { "id": "3", "name": "iPad", "category_name": "Gadgets" } And I wrote an enum: enum : Int { case fruits = 0, fashion, gadgets } var data = [Categories: [[String: Any]]]() Then I have this method to sort the categories: func sortData() { data[.fruits] = self.json.filter({ $0[

问题 Okay, so after going through the tutorials on numpy's structured arrays I am able to create some simple examples: from numpy import array, ones names=['scalar', '1d-array', '2d-array'] formats=['float64', '(3,)float64', '(2,2)float64'] my_dtype = dict(names=names, formats=formats) struct_array1 = ones(1, dtype=my_dtype) struct_array2 = array([(42., [0., 1., 2.], [[5., 6.],[4., 3.]])], dtype=my_dtype) (My intended use case would have more than three entries and would use very long 1d-arrays.)

问题 I'm getting this error: ex = {"The binary operator Equal is not defined for the types 'MySite.Domain.DomainModel.EntityFramework.NickName' and 'System.Int32'."} What I tried to do was do a select all where the NickNameId = someIntPassedIn ... the problem is that the NickNameId is a foreign key, so when it compares the someIntPassedIn to the NickNameId it pulls the whole NickName object that the NickNameId refers to and tries to compare the int to that object. I need a solution here to allow

问题 I have done below code with Swift 2.2, but when switched to Swift 3.0 getting error at if condition "Binary operator '??' cannot be applied to operands of type 'AnyObject?' and 'String'" if let custID = dataDict["cust_id"] ?? "", let custName = dataDict["cust_name"] ?? "", let fileName = dataDict["filename"] ?? "", let transNumber = dataDict["trans_no"] ?? "" { linesheet_custID = (custID["text"] ?? "" ) as! String linesheet_custName = (custName["text"] ?? "" ) as! String linesheet_filename =

问题 In what order are the following parameters tested (in C++)? if (a || b && c) { } I've just seen this code in our application and I hate it, I want to add some brackets to just clarify the ordering. But I don't want to add the brackets until I know I'm adding them in the right place. Edit: Accepted Answer & Follow Up This link has more information, but it's not totally clear what it means. It seems || and && are the same precedence, and in that case, they are evaluated left-to-right. http:/

问题 class MyClass { enum MyEnum { case FirstCase case SecondCase(Int) case ThirdCase } var state:MyEnum! func myMethod () { if state! == MyEnum.FirstCase { // Do something } } } I get the compiler error pointing at the if statement:: Binary operator '==' cannot be applied to two 'MyClass.MyEnum' operands If instead, I use a switch statement, there is no problem: switch state! { // Also, why do I need `!` if state is already an // implicitly unwrapped optional? Is it because optionals also // are