variadic-functions

问题 Suppose I have a call to a function which takes a variable number of arguments in my source code. I want to do some kind of static analysis on this source code to find the type of the arguments being actually passed to the function. For example, if my function call is - foo(a, b, c) I want to find the data type of a, b and c and store this information. 回答1: You pretty well have to do the parse-and-build-a-symbol-table part of compiling the program. Which means running the preprocessor, and

问题 The following code compiles and runs ok. void foo() { } template <typename T, typename... Args> void foo(T x, Args... args) { cout << x << endl; foo(args...); } // inside main() foo(1,1,1); This other code does not compile: void foo() { } template <typename... Args, typename T> void foo(Args... args, T x) { foo(args...); cout << x << endl; } // inside main() foo(1,1,1); The compiler says that there is no matching function for call to foo(1,1,1) and says that foo(Args... args, T x) is a

问题 This question already has answers here : Technically, how do variadic functions work? How does printf work? (2 answers) Closed 5 years ago . If one wants to write a function in C that passes a variable argument list through to printf one has to use the vprintf version. How can I implement this mechanism for a custom function? In other words, how is the essence of what sets vprintf apart from printf implemented in standard conforming C? 回答1: If you want to write a function which takes a va

问题 There seems to be an edge case between the autoboxing and the varargs system for primitive arrays. Is there a clean (i.e. non-reflection) way around this? Example: public class Test { class A<T> { public void a(T... ts) { System.out.println(ts.getClass().getCanonicalName() + " of " + ts[0].getClass().getCanonicalName() + " = " + Arrays.toString(ts)); } } public void test() { // These all work fine - presumably all parameters are autoboxed. new A().a(1, 2, 3); new A().a(1.0, 2.0, 3.0); new A()

问题 According to this answer numeric constants passed to variadic functions are always treated as int if they fit in one. This makes me wonder why the following code works with both, int and long long . Consider the following function call: testfunc(4, 1000, 1001, 1002, 1003); testfunc looks like this: void testfunc(int n, ...) { int k; va_list marker; va_start(marker, n); for(k = 0; k < n; k++) { int x = va_arg(marker, int); printf("%d\n", x); } va_end(marker); } This works fine. It prints 1000,

问题 I have a variadic function with the signature: - (id)initWithNumVertices:(NSUInteger)inCount, ...; But I cannot figure out how to construct the ellipsis part from a variable number of vertices. How can this be done? EDIT: sorry I wasn't asking for a way to write this function, I'm asking for a way to call it, using an unknown number of variables. The function takes structs and not objects. If the number of arguments is known, I can do this: [[MyObject alloc] initWithNumVertices:4, v[0], v[1],

问题 I have a nice C++ function, which supports multiple arguments through va_list + va_start + va_arg. But I had to convert my project to C. After conversion, this va_list construction gets rejected by the compiler (multiple errors). Is there any way to do that thing in C, and (if yes) what I need to change? 回答1: The Wikipedia page on stdarg has probably everything you need. 来源： https://stackoverflow.com/questions/9549947/c-how-to-make-a-function-with-multiple-arguments-va-list

问题 I'm having a hell of a time with the CCMenu class. To create a menu with this class it forces you to call a method called initWithItems, which takes a va_list. I need to generate this list at runtime, and I read that creating a C array and passing that can function just as va_list does under the covers, only it is failing. I have an NSArray of items I want in the va_list, and these items are a SUBCLASS of CCMenuItem, the class that menuWithItems is expecting in the va_list. If you hardcode

问题 I need to analyze a big source code.Code contains several function calls. Depending upon the computation and communication between function calls, i will need to figure out the best configuration scheme for the overall execution of the source code. According to me , Data communicated in calling a function(if it is on different machine,server etc)=Input Data Size+Output Data Size for getting the input data size and output data size ,i think i should rewrite all functions to have variable

问题 I'd like to make a C function which returns a list of tuples, a list of dicts or even better, a list of objects of a class I defined in another python module. The documentation on the C API («The Python/C API») mentions that to build a complex object, I need to call to Py_BuildValue which uses a Variable number of parameters or Py_VaBuildValue which uses a va_list argument. Since C cannot dynamically make a call with a variable number of arguments, I cannot use Py_BuildValue and must use Py