evaluation

问题 1.What data structure to use for electric circuit representation for Kirchoff Rules computation purposes how to differentiate between different types of electric components how to 'recognize' wire inter-connections between them 2.how to implement Kirchoff Rules how to obtain current and voltage loops how to store and evaluate Kirchoff equations [original question text] Specifically, how would the program recognize something is in series and parallel and how will it differentiate between a

问题 Exercise 3.20 in SICP: Draw environment diagrams to illustrate the evaluation of the sequence of expressions (define x (cons 1 2)) (define z (cons x x)) (set-car! (cdr z) 17) (car x) 17 using the procedural implementation of pairs given above. My eyes are destroyed so I cannot draw. I will instead try to imagine as best as I can how the environment model evolves. First, here is the procedural pairs implementation. (define (cons x y) (define (set-x! v) (set! x v)) (define (set-y! v) (set! y v)

问题 Which of the following expressions will always precede left to right in all browsers(particularly IE6+, F3+, Opera 9+, Chrome)? For example the window should always alert first function then second function . In C they always suggest not to depend on the order of the evaluation of expressions. Is the same true for JavaScript or is Operator Precedence consistent? function first(){ alert('first function'); return 0; } function second(){ alert('second function'); return 23; } first() + second();

问题 My question uses Java as an example, but I guess it applies to probably all. Is there any practical difference between the XOR operator ( ^ in Java) and the not-equal-to operator ( != in Java), when comparing booleans? I evaluated things here, but I just kept wondering (seems weird, two things equal)... and didn't find anything on the net. Just one discussion in some forum that ended quickly without any result. 回答1: For Boolean values, they mean the same thing - although there's a compound

问题 If I get a bool variable and set its second bit to 1, then variable evaluates to true and false at the same time. Compile the following code with gcc6.3 with -g option, ( gcc-v6.3.0/Linux/RHEL6.0-2016-x86_64/bin/g++ -g main.cpp -o mytest_d ) and run the executable. You get the following. How can T be equal to true and false at the same time? value bits ----- ---- T: 1 0001 after bit change T: 3 0011 T is true T is false This can happen when you call a function in a different language (say

问题 I'm wondering if it's guaranteed that in a Java program, the boolean expression on the right of a conjunction (exp2 above) will NOT be evaluated as long as the expression on the left (exp1) evaluated to false. I'm wondering because I have an expression like the following: if (var != null && var.somePredicate()) // do something If Java is not guaranteed to stop evaluating (var != null && var.somePredicate()) after it sees that var is null, then it may try to evaluate var.somePredicate() which

问题 This question already has answers here : Is the shortcircuit behaviour of Python's any/all explicit? (4 answers) Closed 2 years ago . I wish to use the Python all() function to help me compute something, but this something could take substantially longer if the all() does not evaluate as soon as it hits a False . I'm thinking it probably is short-circuit evaluated, but I just wanted to make sure. Also, is there a way to tell in Python how the function gets evaluated? 回答1: Yes, it short

问题 I have to convert a MSSQL stored proc that passes a varchar that is a query: INSERT INTO Results EXEC (@Expresion); This isn't working. I'm pretty sure that EXEC and EXECUTE aren't MySQL commands, but CALL doesn't work either. Does anyone know if it's even possible to have something like JavaScript's eval function for MySQL? 回答1: EXECUTE is a valid command in MySQL. MySQL reference manual 回答2: I think you're looking for something like this: SET @queryString = ( SELECT CONCAT('INSERT INTO user

问题 Here is my code: String test = "12+23-42-53+4-31"; int counter = 0; Stack<Integer> numb= new Stack<Integer>(); Stack<String> op = new Stack<String>(); for(int i = 0; i<test.length();i++){ if(test.charAt(i)=='-' || test.charAt(i)=='+'){ int number = Integer.parseInt(test.substring(counter, i)); counter=i+1; numb.push(number); String oper = Character.toString(test.charAt(i)); op.push(oper); } } If I loop through numb stack then the last number of test string is missing. Are there any solutions?

问题 If an expression evaluates multiple && operators, and does not evaluate any operators of lower precedence (eg. || , ?: ), will the expression evaluate to 0 as soon as one of the && s return 0, or will it finish evaluating the remaining && s? For example, q=0; w=1; e=1; r=1; if(q && w && r && e) {} Will this if() evaluate to false as soon as q && w evaluates to 0 (since the remaining && must all evaluate to 0 regardless of the right hand operators)? 回答1: Yes, evaluation will terminate early (