C what is happening when printf convers long long to %o (unsigned int)
c,casting,printf,variadic-functions
while ((n /= 10) > 0) You should be dividing by base. 10 will work like a charm just as long as you ask it to print in decimal. I guess the moral of the story here is that if you have a bug in some code that contains a...
C++ variadic template, recursion decltype
c++,c++11,variadic-templates,variadic-functions
Manipulating types with types is usually easier. template<class K0, class K1, class...Ks> struct my_map; template<class K0, class K1, class...Ks> using my_map_t = typename my_map<K0,K1,Ks...>::type; template<class K0, class K1> struct my_map<K0,K1>{using type=std::map<K0, K1>;}; template<class K0, class K1, class K2, class...Ks> struct my_map<K0, K1, K2, Ks...>{ using type=std::map<K0, my_map_t<K1, K2, Ks...>>; };...
How to specify a variadic (ellipsis) parameter as optional in Swift?
ios,swift,optional-parameters,variadic-functions
It's not possible to have a an optional variadic parameter. The function will always receive an array for the variadic parameter. However, the array can be empty, or the values in the array can be nil. I threw some sample code together, hope it helps communicate what I'm trying to...
Valgrind Conditional jump or move depends of unitialized value(s) when using chained call of variadic functions
c++,c,valgrind,variadic-functions,variadic
As you use summerVariadic(n, args);, you have to provide float summerVariadic(const unsigned int n, va_list args). Since C++11, you may use variadic template instead: template<typename ... Ts> float summerVariadic(Ts... args) { return summerNonVariadic({args...}); } ...
Technically, how do variadic functions work? How does printf work?
The C and C++ standard do not have any requirement on how it has to work. A complying compiler may well decide to emit chained lists, std::stack<boost::any> or even magical pony dust (as per Xeo) under the hood. However, it is usually implemented as follows, even though transformations like inlining...
How to match empty arguments pack in variadic template
c++,templates,variadic-templates,variadic-functions
The easiest solution is adding another indirection: template<typename T> void loadBrush_sub_impl() { // do some work here } template<typename... Targs> void loadBrush_sub(); template<typename T, typename... V> void loadBrush_sub_helper() { loadBrush_sub_impl<T>(); loadBrush_sub<V...>(); } template<typename... Targs> void loadBrush_sub() { loadBrush_sub_helper<Targs...>(); } template<> void loadBrush_sub<>() { } ...
C2780 error when using variadic function
c++11,visual-studio-2013,variadic-templates,variadic-functions
You need one more overload where the recursion can stop: template <typename T> void ConvertLists(QList<QStringList>& converted, T&& c) { converted.append(Convert(std::forward<T>(c))); } template <typename T, typename... Args> void ConvertLists(QList<QStringList>& converted, T&& c, Args&&... args) { converted.append(Convert(std::forward<T>(c))); ConvertLists(converted, std::forward<Args>(args)...); } You may also try the following single-function solution: template...
multiple different sized output function?
matlab,output,variadic-functions
You can also use the varargout option for the function output, which lets you assign (believe it or not) a variable number of outputs. For example, consider this function: function [varargout] = YourFcn(arg1,arg2) A = arg1; B = arg2; varargout = {A;B}; end Then you can call your function and...
Determine types from a variadic function's arguments in C
printf,variadic-functions,va-arg
You can't get actual type information from va_list. You can get what you're looking for from format. What it seems you're not expecting is: none of the arguments know what the actual types are, but format represents the caller's idea of what the types should be. (Perhaps a further hint:...
Including Array of same type in Variadic Templates
c++,variadic-templates,variadic-functions
You may use the following: template <typename T> T sum(const T& v) { return v; } // special case for array template <typename T, std::size_t N> T sum(const T (&v)[N]) { return std::accumulate(std::begin(v), std::end(v), T{}); } template <typename T, typename... Ts> auto sum(const T& v, const Ts&... rest) { return...
How to write a variadic functios in F# emulating a similar Haskell solution
Function, not method. So ParamArray is not an option. The Haskell code you linked is based on the inferred result type. Here's a way to resolve based on the inferred result type in F#: type T = T with static member inline ($) (T, r:'t->'t ) = fun a b...
std::function with C variadic arguments, not templated variable arguments
c++,c++11,varargs,variadic-functions,std-function
This isn't possible with std::function. It's pretty much impossible to forward C-style variadic arguments directly, without knowing what arguments were actually passed. Depending on the circumstances, you might just take a function pointer - a int(*)(const char*, ...), or, if type erasure is necessary, rework your code to use the...
Preserving referenceness when passing variadic arguments
c++,c++11,variadic-templates,variadic-functions,variadic-parameter
During template deduction reference types will deduced to the type that they refer to. So int& will be deduced to an int. This is what is causing the behaviour you are seeing. See here for a more detailed explication....
C++11 strange error with templated functions
c++,templates,c++11,variadic-templates,variadic-functions
Googling for your error message, this looks related to a compiler bug that was reduced to a known Defect Report concerning the trailing return type: 1433. trailing-return-type and point of declaration Section: 3.3.2 [basic.scope.pdecl] Status: extension Submitter: Jason Merrill Date: 2011-12-20 This seems like it should be well-formed: template <class...
What is the meaning of … in parameter list in function prototype? [duplicate]
c,function,argument-passing,variadic-functions
the ... is the notation used to denote variable argument list. This is used in Variadic function. It means, after the fmt, any number of arguments of any type can be passed to err_syserr() function. Famous Example: printf(), scanf()....
Closure annotation for variadic function
javascript,annotations,google-closure-compiler,jsdoc,variadic-functions
"f5" is the expected pattern. /** * @param {...*} var_args * @return {number} */ function f5(var_args) { return arguments.length; } An alternative is: /** @type {function(...*):number} */ function f5() { return arguments.length; } ...
C Variadic Function not working as intended
You should call va_start like this: va_start(list, args); The second parameter of va_start must be the name of the last parameter of test before the ellipsis, which is args....
stdarg.h functionality appears to concatenate arguments wrongly
buf = malloc(sizeof(format) + sizeof(args)); What is this supposed to do? sizeof (format) is just the size of a pointer, 4 bytes for 32-bit system or 8 bytes for 64-bit. sizeof (args) is just another name for sizeof (va_list), which is an implementation-defined type. However, you are using this as...
Iterating through parameters of a variadic function template using variadic lambda
c++,templates,c++11,lambda,variadic-functions
The calls to functor are now unsequenced. The compiler can call functor with your expanded arguments in any order it wants. As an example, IterateThrough3(functor, 1, 2) could do functor(1); functor(2); or it could do functor(2); functor(1);, whereas the other two always do functor(1); functor(2);. Section 8.5.4/4 of the standard...
Building an NSString based on a variadic number of arguments
ios,objective-c,nsstring,variadic-functions,stringwithformat
As Justin pointed out, there is a much simpler way of doing this. NSString has a -initWithFormat:arguments: method that does exactly what you want. Also, your method name has a few issues: Naming convention - you should indicate in the method name its purpose (creating a URL request) You are...
Accessing variadic function arguments without stdarg
There is no portable way to do that -- and no good reason to use any non-portable method (unless you're actually writing <stdarg.h> for a new system). The macros defined in <stdarg.h> have to be implemented somehow. You could examine the contents of that header for your implementation, and possibly...
Are variadic functions deprecated?
c++,c++11,variadic-templates,variadic-functions
Variadic templates are variadic at compile time; variadic functions are variadic at run time. In other words, a variadic template function is compiled to accept however many parameters are passed to it, while a regular variadic function is compiled to accept any number of parameters. You can put a variadic...
Swift and C callbacks with variadic arguments
You need to write a C function instead of an objective C method. Unfortunately Swift will convert these into Swift Closure. However you can write a function/method in objective C to return your function pointer. This will stop Swift being able to convert the function to a closure. i.e in...
Syntax of recursive variadic function in Scala [duplicate]
scala,recursion,variadic-functions
It's called a sequence argument (see the second-to-last paragraph in section 6.6 Function Applications of the Scala Language Specification). It deliberately resembles Type Ascription syntax. In an argument list, it basically means the exact opposite of what Repeated Parameters mean in a parameter list. Repeated parameters mean "take all the...
How can I create a function with a variable number of arguments?
rust,varargs,variadic-functions
In general, you can't - Rust does not support variadic functions, except when interoperating with C code that uses varargs. In this case, since all of your arguments are the same type, you can accept a slice: fn foo(args: &[&str]) { for arg in args { println!("{}", arg); } }...
pack array for variadic
Never say never. Since it appears that you know the size of the list (=sizeof...(args)), you can try your luck with a c++14 library feature and create an index_sequence that you then use for indexing the list during unpacking. Look here: http://en.cppreference.com/w/cpp/utility/integer_sequence. The examples at the bottom show how to...
How to parallel variadic function with TBB parallel_for?
c++,c++11,variadic-templates,tbb,variadic-functions
You can use std::tuple<Ts...> to hold variadic values, and expand it for function invocation with the indices trick. C++14 Standard Library provides std::index_sequence for this purpose. #include <tuple> // forward compatibility for C++14 Standard Library namespace cxx14 { template<std::size_t...> struct index_sequence{}; template<std::size_t N, std::size_t... Is> struct make_index_sequence : make_index_sequence<N-1, N-1,...