overloading

问题 I'd like to write overloaded functions as follows: case class A[T](t: T) def f[T](t: T) = println("normal type") def f[T](a: A[T]) = println("A type") And the result is as I expected: f(5) => normal type f(A(5)) => A type So far so good. But the problem is the same thing doesn't work for Arrays: def f[T](t: T) = println("normal type") def f[T](a: Array[T]) = println("Array type") Now the compiler complains: double definition: method f:[T](t: Array[T])Unit and method f:[T](t: T)Unit at line 14

问题 This question already has answers here : Closed 8 years ago . Possible Duplicates: Why can't my C++ compiler deduce template argument for boost function? Isn't the template argument (the signature) of std::function part of its type? I have the following: #include <functional> void Foo( std::function<void()> ); void Foo( std::function<void(int)> ); void Bar(); int main() { Foo( Bar ); // Error: ambiguous Foo( [](){} ); // Error: ambiguous Foo( std::function<void()>( Bar ) ); // Ok Foo( std:

问题 Having issues with adding objects. It seems to work when adding two, ex: 2.34 + 34.57 = 36.81, but fails when adding 3 or more ex: 6.78 + 9.81 + 4.59 = 79.59 <-- the total seems to increase drastically for some reason. The converter functions can be ignored since they simply translate the numerical total to english format and are working. The median and sorting, and > functions work as well, so the issue might be somewhere in the ostream, istream, or + functions. I used cout a whole bunch of

问题 Having issues with adding objects. It seems to work when adding two, ex: 2.34 + 34.57 = 36.81, but fails when adding 3 or more ex: 6.78 + 9.81 + 4.59 = 79.59 <-- the total seems to increase drastically for some reason. The converter functions can be ignored since they simply translate the numerical total to english format and are working. The median and sorting, and > functions work as well, so the issue might be somewhere in the ostream, istream, or + functions. I used cout a whole bunch of

问题 Is this allowed? Class A{ ... ... }; A a; //Global object int main() { A a; // Local object . . . . return 0; } Here a global object has been declared after the class definition, but also a local variable has been declared. Is it ok? Why? 回答1: It's perfectly legal to "hide" the declaration of an object, with another declaration in tighter scope. Within your main function, a will refer to the local variable. Outside the main function, a will refer to the global variable. As to whether it's "ok

问题 Is this allowed? Class A{ ... ... }; A a; //Global object int main() { A a; // Local object . . . . return 0; } Here a global object has been declared after the class definition, but also a local variable has been declared. Is it ok? Why? 回答1: It's perfectly legal to "hide" the declaration of an object, with another declaration in tighter scope. Within your main function, a will refer to the local variable. Outside the main function, a will refer to the global variable. As to whether it's "ok

问题 Im having trouble figuring out how to implement the equivalent of overloading the assignment operator in C++ to Java. I know there is no such thing, but I need to simulate it. I've tried overriding the Clone() function, but no luck. Any ideas? Below is my main Queue p = new Queue(); Queue q = new Queue(); p.enqueue('a'); p.enqueue(9); p.enqueue(10); p.enqueue(310); p.enqueue(8); q = p; System.out.print(p); And here is the clone function public void Clone(Queue other) throws Throwable { System

问题 I'm trying to extend Dictionary and allow extracting values casted to a certain types and with a given default value. For this I added two overloads for the subscript function, one with a default value, one without: extension Dictionary { subscript<T>(_ key: Key, as type: T.Type, defaultValue: T?) -> T? { // the actual function is more complex than this :) return nil } subscript<T>(_ key: Key, as type: T.Type) -> T? { // the following line errors out: // Extraneous argument label

问题 I'm trying to extend Dictionary and allow extracting values casted to a certain types and with a given default value. For this I added two overloads for the subscript function, one with a default value, one without: extension Dictionary { subscript<T>(_ key: Key, as type: T.Type, defaultValue: T?) -> T? { // the actual function is more complex than this :) return nil } subscript<T>(_ key: Key, as type: T.Type) -> T? { // the following line errors out: // Extraneous argument label

问题 This question already has answers here : Two methods with the same name in java (3 answers) Closed 6 years ago . I tried the following code public class HelloWorld { public void printData(Test t) { System.out.println("Reached 1"); } public void printData(newTest t) { System.out.println("Reached 2"); } public void printData(newTest1 t) { System.out.println("Reached 3"); } public static void main(String args[]) { Test t1 = new Test(); HelloWorld h = new HelloWorld(); h.printData(t1); NewTest t2