parameters

问题 This question already has answers here : How to access a local variable from a different function using pointers? (9 answers) Closed 6 years ago . I found this question on my study guide, and I am not sure why it would be bad to return a pointer to a local variable/parameter. Any ideas? 回答1: It's not so much a "bad practice" (implying that it might cause problems) as much as it is a practice that will absolutely cause undefined behavior . It's like dereferencing a null pointer: don't do it

问题 This question already has answers here : How to access a local variable from a different function using pointers? (9 answers) Closed 6 years ago . I found this question on my study guide, and I am not sure why it would be bad to return a pointer to a local variable/parameter. Any ideas? 回答1: It's not so much a "bad practice" (implying that it might cause problems) as much as it is a practice that will absolutely cause undefined behavior . It's like dereferencing a null pointer: don't do it

问题 This question already has answers here : Can I pass an array as arguments to a method with variable arguments in Java? (5 answers) Java, 3 dots in parameters (9 answers) Closed 6 years ago . I am wondering how the parameter of ... works in Java. For example: public void method1(boolean... arguments) { //... } Is this like an array ? How I should access the parameter? 回答1: Its called Variable arguments or in short var-args , introduced in Java 1.5. The advantage is you can pass any number of

问题 I am in the process of converting several queries which were hard-coded into the application and built on the fly to parameterized queries. I'm having trouble with one particular query, which has an in clause: UPDATE TABLE_1 SET STATUS = 4 WHERE ID IN (1, 14, 145, 43); The first parameter is easy, as it's just a normal parameter: MySqlCommand m = new MySqlCommand("UPDATE TABLE_1 SET STATUS = ? WHERE ID IN (?);"); m.Parameters.Add(new MySqlParameter("", 2)); However, the second parameter is a

问题 I have the following function: function ypdiff = ypdiff(t,y) a = 0.01; b = 0.1; ypdiff(1) = -a*y(1)*y(2); ypdiff(2) = b*y(1)*y(2)-b*y(2); ypdiff(3) = b*y(2); ypdiff = [ypdiff(1) ypdiff(2) ypdiff(3)]'; If I want to solve this, I would call the ode45 function as follows: [t y] = ode45(@ypdiff, [to tf], yo); But if I want to pass a parameter to this function, how would I use the ode45 function? Specifically, I am trying for the following formulation: function ypdiff = ypdiff(t,y,u) a = 0.01; b =

问题 I'm trying to compile the following piece of code, I get an error on the line which specializes std::vector, it seems the one parameter being passed-in is somehow being assumed to be two parameters. Is it perhaps something to do with angle-brackets? Is there a special way/mechanism where by such parameters can be correctly passed to the macro? #include <vector> template<typename A> struct AClass {}; #define specialize_AClass(X)\ template<> struct AClass<X> { X a; }; specialize_AClass(int) /

问题 I use Entity Framework 4.1 Code First. I want to call a stored procedure that has an output parameter and retrieve the value of that output parameter in addition to the strongly typed result set. Its a search function with a signature like this public IEnumerable<MyType> Search(int maxRows, out int totalRows, string searchTerm) { ... } I found lots of hints to "Function Imports" but that is not compatible with Code First. I can call stored procedures using Database.SqlQuery(...) but that does

问题 In the work I do, I often have parameters that I need to group into subsets for convenience: d1 = {'x':1,'y':2} d2 = {'a':3,'b':4} I do this by passing in multiple dictionaries. Most of the time I use the passed dictionary directly, i.e.: def f(d1,d2): for k in d1: blah( d1[k] ) In some functions I need to access the variables directly, and things become cumbersome; I really want those variables in the local name space. I want to be able to do something like: def f(d1,d2) locals().update(d1)

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: What's the difference between an argument and a parameter? I was going through some interview questions. I wasn't able to come up with a solid answer to this question: Difference between arguments and parameters in Java? How are they different? 回答1: Generally a parameter is what appears in the definition of the method. An argument is the instance passed to the method during runtime. You can see a description

问题 Could someone please give me some sample code that uses an output parameter in function? I've tried to Google it but just found it just in functions. I'd like to use this output value in another function. The code I am developing intended to be run in Android. 回答1: Java passes by value; there's no out parameter like in C#. You can either use return , or mutate an object passed as a reference ( by value). Related questions Does Java have something like C#'s ref and out keywords? ? (NO!) Is