variadic-functions | 易学教程

Java, 3 dots in parameters

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问题 What do the 3 dots in the following method mean? public void myMethod(String... strings){ // method body } 回答1: It means that zero or more String objects (or an array of them) may be passed as the argument(s) for that method. See the "Arbitrary Number of Arguments" section here: http://java.sun.com/docs/books/tutorial/java/javaOO/arguments.html#varargs In your example, you could call it as any of the following: myMethod(); // Likely useless, but possible myMethod("one", "two", "three");

Arrays.asList() not working as it should?

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问题 I have a float[] and i would like to get a list with the same elements. I could do the ugly thing of adding them one by one but i wanted to use the Arrays.asList method. There is a problem though. This works: List<Integer> list = Arrays.asList(1,2,3,4,5); But this does not. int[] ints = new int[] {1,2,3,4,5}; List<Integer> list = Arrays.asList(ints); The asList method accepts a varargs parameter which to the extends of my knowledge is a \"shorthand\" for an array. Questions: Why does the

Variable number of arguments in C++?

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问题 How can I write a function that accepts a variable number of arguments? Is this possible, how? 回答1: You probably shouldn't, and you can probably do what you want to do in a safer and simpler way. Technically to use variable number of arguments in C you include stdarg.h. From that you'll get the va_list type as well as three functions that operate on it called va_start() , va_arg() and va_end() . #include<stdarg.h> int maxof(int n_args, ...) { va_list ap; va_start(ap, n_args); int max = va_arg

Passing an array to a function with variable number of args in Swift

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In The Swift Programming Language , it says: Functions can also take a variable number of arguments, collecting them into an array. func sumOf(numbers: Int...) -> Int { ... } When I call such a function with a comma-separated list of numbers (`sumOf(1, 2, 3, 4), they are made available as an array inside the function. Question: what if I already have an array of numbers that I want to pass to this function? let numbers = [1, 2, 3, 4] sumOf(numbers) This fails with a compiler error, “Could not find an overload for '__conversion' that accepts the supplied arguments”. Is there a way to turn an