variadic-functions

This question already has answers here : How to pass variable number of arguments to printf/sprintf (7 answers) I'd like to have a helper function log that essentially does the following: log(file, "array has %d elements\n", 10); // writes "2014-02-03 16:33:00 - array has 10 elements" to &file I have the time portion down, and I have the file writing portion down. However, the problem is the method signature itself for log — what should I put? This says that the printf declaration ends with the ... keyword, but how can I use this in my function? void log(FILE *f, const char * format, ...) //

I have a method which takes a variable length string (String...) as parameter. I have a List<String> with me. How can I pass this to the method as argument? FloF String... equals a String[] So just convert your list to a String[] and you should be fine. String ... and String[] are identical If you convert your list to array. using Foo[] array = list.toArray(new Foo[list.size()]); or Foo[] array = new Foo[list.size()]; list.toArray(array); then use that array as String ... argument to function. You can use stream in java 8. String[] array = list.stream().toArray(String[]::new); Then the array

I run cl /P test.cpp, the file and result is as following. test.cpp #define FiltedLog( ...) \ if (logDetail) \ MP_LOG(LOG_INFO, __VA_ARGS__); #define MP_LOG(level,fmt,...) \ BOOAT::LOG("MP", level, fmt, ##__VA_ARGS__) #define LOG(tag,level,fmt,...) \ Log::log(tag, level, "%s: " fmt, __PRETTY_FUNCTION__, ##__VA_ARGS__) int main () { FiltedLog ( "abc", 1, 2); } Cl /P test.cpp : #line 1 "test.cpp" int main () { if (logDetail) BOOAT::Log::log("MP", LOG_INFO, "%s: " "abc", 1, 2, __PRETTY_FUNCTION__ );; } I wonder why the __PRETTY_FUNCTION__ are put as the last arguments in the result. I assume the

I am used to declaring variadic functions like this: int f(int n, ...); When reading The C++ Programming Language I found that the declarations in the book omit the comma: int f(int n...); // the comma has been omitted It seems like this syntax is C++ specific as I get this error when I try to compile it using a C compiler: test.c:1:12: error: expected ‘;’, ‘,’ or ‘)’ before ‘...’ token int f(int n...); Is there any difference between writing int f(int n, ...) and int f(int n... )? Why was this syntax added C++? kfsone According to § 8.3.5.4 of the C++ standard ( current draft ): Where

/* Debugging */ #ifdef DEBUG_THRU_UART0 # define DEBUG(...) printString (__VA_ARGS__) #else void dummyFunc(void); # define DEBUG(...) dummyFunc() #endif I've seen this notation in different headers of C programming, I basically understood it's passing arguments, but I didn't understand what this "three dots notation" is called? Can someone explain it with example or provide links also about VA Args? The dots are called, together with the __VA_ARGS__ , variadic macros When the macro is invoked, all the tokens in its argument list [...], including any commas, become the variable argument . This

I'm trying to migrate Java 7 code to Java 8, so I've code similar to: package tests; import java.util.Arrays; import java.util.Map; public class Tests { private static interface ComparableMap<K,V> extends Map<K,V>, Comparable {} public static void main(String[] args) { func(getString()); } private static void func(Comparable...input){ System.out.println(Arrays.toString(input)); } private static void func(ComparableMap <?,?> m){ System.out.println(m); } private static <T extends Comparable> T getString(){ return (T) "aaa"; } } In java 7 it working properly, in java 8 I'm getting: java.lang

I don't understand that syntax. Trying to google various words plus "..." is useless. Margus This is called Variadic function (wiki page with examples in many languges). In computer programming, a variadic function is a function of indefinite arity, i.e. one which accepts a variable number of arguments. Support for variadic functions differs widely among programming languages. There are many mathematical and logical operations that come across naturally as variadic functions. For instance, the summing of numbers or the concatenation of strings or other sequences are operations that can

Is it possible a lambda function to have variable number of arguments? For example, I want to write a metaclass, which creates a method for every method of some other class and this newly created method returns the opposite value of the original method and has the same number of arguments. And I want to do this with lambda function. How to pass the arguments? Is it possible? class Negate(type): def __new__(mcs, name, bases, _dict): extended_dict = _dict.copy() for (k, v) in _dict.items(): if hasattr(v, '__call__'): extended_dict["not_" + k] = lambda s, *args, **kw: not v(s, *args, **kw) return