evaluation

问题 Let\'s take a simple example of an object Cat . I want to be sure the \"not null\" cat is either orange or grey. if(cat != null && cat.getColor() == \"orange\" || cat.getColor() == \"grey\") { //do stuff } I believe AND comes first, then the OR. I\'m kinda fuzzy though, so here are my questions: Can someone walk me through this statement so I\'m sure I get what happens? Also, what happens if I add parentheses; does that change the order of operations? Will my order of operations change from

问题 Why does below code fail to compile? package main import ( \"fmt\" \"unsafe\" ) var x int = 1 const ( ONE int = 1 MIN_INT int = ONE << (unsafe.Sizeof(x)*8 - 1) ) func main() { fmt.Println(MIN_INT) } I get an error main.go:12: constant 2147483648 overflows int Above statement is correct. Yes, 2147483648 overflows int (In 32 bit architecture). But the shift operation should result in a negative value ie -2147483648. But the same code works, If I change the constants into variables and I get the

问题 This question already has answers here : Evaluating string “3*(4+2)” yield int 18 [duplicate] (14 answers) Closed 6 years ago . Is there an easy way to evaluate strings like \"(4+8)*2\" So that you\'d get the int value of 24? Or is there a lot of work needed to get this done...? 回答1: Use Ncalc: Expression e = new Expression("(4+8)*2"); Debug.Assert(24 == e.Evaluate()); http://ncalc.codeplex.com/ Also, this question had been previously asked and has some interesting answers including Ncalc :

问题 There are many algorithms to evaluate expressions, for example: By Recursive Descent Shunting-yard algorithm Reverse Polish notation Is there any way to evaluate any mathematical expression using C# .net reflection or other modern .net technology? 回答1: Further to Thomas's answer, it's actually possible to access the (deprecated) JScript libraries directly from C#, which means you can use the equivalent of JScript's eval function. using Microsoft.JScript; // needs a reference to Microsoft

问题 I know that you can use \' (aka quote ) to create a list, and I use this all the time, like this: > (car \'(1 2 3)) 1 But it doesn’t always work like I’d expect. For example, I tried to create a list of functions, like this, but it didn’t work: > (define math-fns \'(+ - * /)) > (map (lambda (fn) (fn 1)) math-fns) application: not a procedure; expected a procedure that can be applied to arguments given: \'+ When I use list , it works: > (define math-fns (list + - * /)) > (map (lambda (fn) (fn

问题 Say I create one object and add it to my ArrayList . If I then create another object with exactly the same constructor input, will the contains() method evaluate the two objects to be the same? Assume the constructor doesn\'t do anything funny with the input, and the variables stored in both objects are identical. ArrayList<Thing> basket = new ArrayList<Thing>(); Thing thing = new Thing(100); basket.add(thing); Thing another = new Thing(100); basket.contains(another); // true or false? class

问题 This question already has an answer here: Why are these constructs using pre and post-increment undefined behavior? 14 answers Can it be assumed a evaluation order of the function parameters when calling it in C ? According to the following program, it seems that there is not a particular order when I executed it. #include <stdio.h> int main() { int a[] = {1, 2, 3}; int * pa; pa = &a[0]; printf(\"a[0] = %d\\ta[1] = %d\\ta[2] = %d\\n\",*(pa), *(pa++),*(++pa)); /* Result: a[0] = 3 a[1] = 2 a[2]