variadic-functions

问题 I have some code that converts variadic parameters into a va_list , then passes the list on to a function that then calls vsnprintf . This works fine on Windows and OS X, but it is failing with odd results on Linux. In the following code sample: #include <string.h> #include <stdio.h> #include <stdarg.h> #include <stdlib.h> char *myPrintfInner(const char *message, va_list params) { va_list *original = &params; size_t length = vsnprintf(NULL, 0, message, *original); char *final = (char *)

问题 This question already has an answer here : Why can't std::function bind to C-style variadic functions? (1 answer) Closed 6 years ago . I have a structure that I pass around my application which contains a bunch of callback functions: typedef struct { std::function<void (void)> f1; std::function<void (int)> f2; std::function<int (float *)> f3; // ... and so on } CallbackTable; I handle state control within the application by binding different functions to the various callbacks, depending upon

问题 I have a function that takes 3 arguments. a vector of other functions, a void*, and an arbitrary list of arguments. The function is designed to pass in it's void* and arbitrary list of arguments to each function in the list, which the functions will handle themselves. here is an example of what I want: typedef void (*fptr)(const void* userdata, ...); void execute_all(vector<fptr> funcs, void* userdata, ...){ for (int i = 0;i<funcs.size();i++){ fptr func = funcs[i]; //execute func with

问题 I have a function that takes 3 arguments. a vector of other functions, a void*, and an arbitrary list of arguments. The function is designed to pass in it's void* and arbitrary list of arguments to each function in the list, which the functions will handle themselves. here is an example of what I want: typedef void (*fptr)(const void* userdata, ...); void execute_all(vector<fptr> funcs, void* userdata, ...){ for (int i = 0;i<funcs.size();i++){ fptr func = funcs[i]; //execute func with

问题 This question already has answers here : How to pass an ArrayList to a varargs method parameter? (5 answers) Closed 3 years ago . List<String> strings; void takeParams(String... params); How can I pass the list into that a method only taking varargs? strings.toArray(); is not possible as it returns Object[] . 回答1: Use the List#toArray(T[]) method to create an array from the list, and pass it. takeParams(strings.toArray(new String[strings.size()])); 来源： https://stackoverflow.com/questions

问题 I have a need for a variadic version of R.either . After doing some searching around the web, I have not found a solution. R.anyPass would work but it returns a Boolean instead of the original value. Is there already a solution that I have overlooked? If not, what would be the most optimal way to write a variadic either utility function? An example: const test = variadicEither(R.multiply(0), R.add(-1), R.add(1), R.add(2)) test(1) // => 2 回答1: You could use a combination of reduce + reduced :

问题 I have a need for a variadic version of R.either . After doing some searching around the web, I have not found a solution. R.anyPass would work but it returns a Boolean instead of the original value. Is there already a solution that I have overlooked? If not, what would be the most optimal way to write a variadic either utility function? An example: const test = variadicEither(R.multiply(0), R.add(-1), R.add(1), R.add(2)) test(1) // => 2 回答1: You could use a combination of reduce + reduced :

问题 I have a need for a variadic version of R.either . After doing some searching around the web, I have not found a solution. R.anyPass would work but it returns a Boolean instead of the original value. Is there already a solution that I have overlooked? If not, what would be the most optimal way to write a variadic either utility function? An example: const test = variadicEither(R.multiply(0), R.add(-1), R.add(1), R.add(2)) test(1) // => 2 回答1: You could use a combination of reduce + reduced :

问题 I have a need for a variadic version of R.either . After doing some searching around the web, I have not found a solution. R.anyPass would work but it returns a Boolean instead of the original value. Is there already a solution that I have overlooked? If not, what would be the most optimal way to write a variadic either utility function? An example: const test = variadicEither(R.multiply(0), R.add(-1), R.add(1), R.add(2)) test(1) // => 2 回答1: You could use a combination of reduce + reduced :

问题 Here's what libc has to say about variadic functions: Since the prototype doesn’t specify types for optional arguments, in a call to a variadic function the default argument promotions are performed on the optional argument values. This means the objects of type char or short int (whether signed or not) are promoted to either int or unsigned int, as appropriate; and that objects of type float are promoted to type double. So, if the caller passes a char as an optional argument, it is promoted