Just write this: const std::size_t n = sizeof…(T); //you may use `constexpr` instead of `const` Note that n is a constant expression (i.e known at compile-time), which means you may use it where constant expression is needed, such as: std::array<int, n> a; //array of n elements std::array<int, 2*n> b; //array of (2*n) elements auto middle … Read more
That’s an old-style function declaration. This declaration: void foo(); declares that foo is a function returning void that takes an unspecified but fixed number and type(s) of arguments. It doesn’t mean that calls with arbitrary arguments are valid; it means that the compiler can’t diagnose incorrect calls with the wrong number or type of arguments. … Read more
You can either Widen or Box but you cannot do both, unless you are boxing and widening to Object (An int to Integer(Boxing) and then Integer to Object(Widening) is legal, since every class is a subclass of Object, so it is possible for Integer to be passed to Object parameter) Similarly an int to Number … Read more
If you look at what va_start expands out to, you’ll see what’s happening: va_start(argptr, format); becomes (roughly) argptr = (va_list) (&format+1); If format is a value-type, it gets placed on the stack right before all the variadic arguments. If format is a reference type, only the address gets placed on the stack. When you take … Read more
The only difference between the two is the way you call the function. With String var args you can omit the array creation. public static void main(String[] args) { callMe1(new String[] {“a”, “b”, “c”}); callMe2(“a”, “b”, “c”); // You can also do this // callMe2(new String[] {“a”, “b”, “c”}); } public static void callMe1(String[] args) … Read more
You could try to use call_user_func_array. But I’ve never tried it on a built-in function before. Here is an example: $dynamicSort = “$sort1,SORT_ASC,$sort2,SORT_ASC,$sort3,SORT_ASC”; $param = array_merge(explode(“,”, $dynamicSort), array($arrayToSort)) call_user_func_array(‘array_multisort’, $param)
The *args and **kwargs is a common idiom to allow arbitrary number of arguments to functions as described in the section more on defining functions in the Python documentation. The *args will give you all function parameters as a tuple: def foo(*args): for a in args: print(a) foo(1) # 1 foo(1,2,3) # 1 # 2 … Read more
AFAIK ObjectiveC (just like C and C++) do not provide you with a syntax that allows what you directly have in mind. The usual workaround is to create two versions of a function. One that may be called directly using … and another one called by others functions passing the parameters in form of a … Read more
The general rule that applies here is this: if one method signature is strictly more specific than the other, then Java chooses it without an error. Intuituively, a method signature is more specific if you could delete it entirely and the other, less specific one would be applicable to each existing invocation. When presented with … Read more
You can’t, you can only pass the arguments as a va_list. See the comp.lang.c FAQ. In general, if you’re writing variadic functions (that is, functions which take a variable number of arguments) in C, you should write two versions of each function: one which takes an ellipsis (…), and one which takes a va_list. The … Read more