variadic-functions

I have question: what is the difference between these two declarations? public static void printMax(double... numbers) { ... } public static void printmax(double numbers[]) { ... } Is double... numbers the same as double numbers[] ? polygenelubricants On varargs The Type... construct in method parameter declaration is commonly what is called varargs. In JLS, it's called the variable arity parameter. JLS 8.4.1 Format parameters The last formal parameter in a list is special; it may be a variable arity parameter, indicated by an elipsis following the type. If the last formal parameter is a

In this document , the author said Only a POD-type can be an argument for the ellipsis "..." while std::string is not a POD-type. I'm understanding this as Passing NON-POD type to Variadic function is undefined behavior . Is it right? Though, is he saying C/C++ standard? I tried to find it at n3242 C++ spec. But can not find. I'd like to know I'm understanding rightly and this is a standard. Mike Seymour It's specified in C++11 5.2.2/7: Passing a potentially-evaluated argument of class type having a non-trivial copy constructor, a non-trivial move contructor, or a non-trivial destructor, with

I'm trying to use C stdarg.h lib, with a generic type. The type int, is my generic type > to understand it, please, hold reading. So, my problem is: I have a function that accept variable number of arguments. like void function (int paramN, ...); In my program, there are no way to know, which is the type of variable arguments, it can be a char, an array, an int, an short, an function point, etc... like function (paramN, "Hey, I'm a string", 1, function_pint, array, -1); // -1 is a sentinel. So, I think that, an int, is 32bits, in a x86(32bits) system, this will hold all address of memory. So,

A lot of MATLAB functions have an input structure such as: output = function MyFun(a,b,c,'-setting1',s1,'-setting2',s2,'-setting3',s3) I am wondering how I should implement this kind of functionality in my own functions. To be precise, I would like to find out how I can create a function such that: The function has a variable number of inputs N + M The first N inputs are ordered and unlabeled . In the example above, N = 3 . The first input is always a , second input is always b , third input is always c . The function input is variable in that users do not necessarily need to send b , c ; when

How can I write (if it's possible at all...) a function which takes an unknown number of parameters in C99 (the return type is constant)? jbx Yes you can do it in C using what are referred to as Variadic Functions. The standard printf() and scanf() functions do this, for example. Put the ellipsis (three dots) as the last parameter where you want the 'variable number of parameters to be. To access the parameters include the <stdarg.h> header: #include <stdarg.h> And then you have a special type va_list which gives you the list of arguments passed, and you can use the va_start , va_arg and va

I have a function void foo(int cnt, va_list ap); I need to use it, but requirement is quite strict, number of va_list vary and it will change during run-time. What I would like to do is: create a va_list (which expects char* ) form QList<Contact*> where Contact is a defined class class Contact { public: QString getName(); private: QString m_name; }; and I would like to populate in the loop va_list for example: for (int idx = 0; idx<contacts.count(); idx++) { contacts.at(idx)->getName(); // this i would like to pass to va_list } Does anybody have a clue about how I could do this? What you're

Is it possible to create a PHP function that takes a variable number of parameters all of them by reference? It doesn't help me a function that receives by reference an array of values nor a function that takes its arguments wrapped in an object because I'm working on function composition and argument binding. Don't think about call-time pass-by-reference either. That thing shouldn't even exist. PHP 5.6 introduced new variadic syntax which supports pass-by-reference. (thanks @outis for the update) function foo(&...$args) { $args[0] = 'bar'; } For PHP 5.5 or lower you can use the following

I am looking to do this in C/C++. I came across Variable Length Arguments but this suggests a solution with Python & C using libffi . Now, if I want to wrap printf function with myprintf What I do is like below: void myprintf(char* fmt, ...) { va_list args; va_start(args,fmt); printf(fmt,args); va_end(args); } int _tmain(int argc, _TCHAR* argv[]) { int a = 9; int b = 10; char v = 'C'; myprintf("This is a number: %d and \nthis is a character: %c and \n another number: %d\n",a, v, b); return 0; } But the results are not as expected! This is a number: 1244780 and this is a character: h and

variadic template is introduced in c++11. And I found the printf function can be replaced using it. However, cout is used in the implementation. I am wondering if it is possible to use something else to achieve type safe but not sacrifice too much performance. void safe_printf(const char *s) { while (*s) { if (*s == '%') { if (*(s + 1) == '%') { ++s; } else { throw "invalid format string: missing arguments"; } } std::cout << *s++; } } template<typename T, typename... Args> void safe_printf(const char *s, T& value, Args... args) { while (*s) { if (*s == '%') { if (*(s + 1) == '%') { ++s; } else