variadic-functions

问题 I'm afraid of varargs. I don't know what to use them for. Plus, it feels dangerous to let people pass as many arguments as they want. What's an example of a context that would be a good place to use them? 回答1: Varargs are useful for any method that needs to deal with an indeterminate number of objects . One good example is String.format. The format string can accept any number of parameters, so you need a mechanism to pass in any number of objects. String.format("This is an integer: %d",

问题 I'm afraid of varargs. I don't know what to use them for. Plus, it feels dangerous to let people pass as many arguments as they want. What's an example of a context that would be a good place to use them? 回答1: Varargs are useful for any method that needs to deal with an indeterminate number of objects . One good example is String.format. The format string can accept any number of parameters, so you need a mechanism to pass in any number of objects. String.format("This is an integer: %d",

问题 I'm afraid of varargs. I don't know what to use them for. Plus, it feels dangerous to let people pass as many arguments as they want. What's an example of a context that would be a good place to use them? 回答1: Varargs are useful for any method that needs to deal with an indeterminate number of objects . One good example is String.format. The format string can accept any number of parameters, so you need a mechanism to pass in any number of objects. String.format("This is an integer: %d",

问题 This question already has answers here : Why doesn't Java's main use a variable length argument list? (8 answers) Closed 3 years ago . I was converting a Groovy codebase into Java and forgot to change public static void main(String... args) { to public static void main(String args[]) { and compiled and ran the project all this time only to be surprised only now that this is legal Java 8 code. I understand that Java 8 Varargs makes it possible for a function to have arbitrary number of

问题 This question already has answers here : Why doesn't Java's main use a variable length argument list? (8 answers) Closed 3 years ago . I was converting a Groovy codebase into Java and forgot to change public static void main(String... args) { to public static void main(String args[]) { and compiled and ran the project all this time only to be surprised only now that this is legal Java 8 code. I understand that Java 8 Varargs makes it possible for a function to have arbitrary number of

问题 I really wonder how printf executed. Is there a parameter array structure in C? Can i define my custom function like printf? 回答1: A special type va_list is used for using variable list arguements. read this. 回答2: You could use the va_arg macro. Here's an example #include <stdio.h> /* printf */ #include <stdarg.h> /* va_list, va_start, va_arg, va_end */ int FindMax (int n, ...) { int i,val,largest; va_list vl; va_start(vl,n); largest=va_arg(vl,int); for (i=1;i<n;i++) { val=va_arg(vl,int);

问题 In the following method definitions, what does the * and ** do for param2 ? def foo(param1, *param2): def bar(param1, **param2): 回答1: The *args and **kwargs is a common idiom to allow arbitrary number of arguments to functions as described in the section more on defining functions in the Python documentation. The *args will give you all function parameters as a tuple: def foo(*args): for a in args: print(a) foo(1) # 1 foo(1,2,3) # 1 # 2 # 3 The **kwargs will give you all keyword arguments

问题 This question already has answers here : Passing variable arguments to another function that accepts a variable argument list (8 answers) Closed 5 years ago . I have a function log_message it takes variable arguments. log_message(int level, char *fmt, ...) now before calling this( log_message ) function i have to add new function( _log_message ), and new function will call log_message . _log_message(int level, char *fmt, ...) new function is also same. when _log_message will call log_message

问题 The idea here is to make a class that constructs with a function and an array of parameters and calls that function in a new thread. This is my class so far: class FunctionThread extends Thread { public function __construct($fFunction, $aParameters){ $this->fFunction = $fFunction; $this->aParameters = $aParameters; } public function run(){ $this->fFunction($this->aParmeters[0], $this->aParmeters[1], ...); } } Obviously the run function is incorrect, which brings me to my question: Assuming

问题 I'm trying to make some improvements to a interpreter for microcontrollers that I'm working on. For executing built-in functions I currently have something like this (albeit a bit faster): function executeBuiltin(functionName, functionArgs) { if (functionName=="foo") foo(getIntFromArg(functionArgs[0])); if (functionName=="bar") bar(getIntFromArg(functionArgs[0]),getBoolFromArg(functionArgs[1]),getFloatFromArg(functionArgs[2])); if (functionName=="baz") baz(); ... } But it is for an embedded