function-pointers

问题 So I'm trying to write a buffering library for the 64th time and I'm starting get into some pretty advanced stuff. Thought I'd ask for some proffesional input on this. In my first header file I have this: typedef struct StdBuffer { void* address; } StdBuffer; extern void StdBufferClear(StdBuffer); In another header file that #includes the first header file I have this: typedef struct CharBuffer { char* address; } CharBuffer; void (*CharBufferClear)(CharBuffer) = (void*) StdBufferClear; Will

问题 I was under the impression that I could use reference_wrapper to generate a functor that would return the object passed into the reference_wrapper ctor. But this isn't working. Am I doing it wrong? If so is there a better way to accomplish this? I can write a lambda, it just seems like I shouldn't have to. #include <iostream> #include <functional> using namespace std; void funPtrPrinter( function< int( void ) > output ) { cout << output() << endl; } int main( void ) { int thirteen = 13; auto

问题 This is not something most people would probably use, but it just came to mind and was bugging me. Is it possible to have some machine code in say, a c-string, and then cast its address to a function pointer and then use it to run that machine code? 回答1: In theory you can, per Carl Norum. This is called "self-modifying code." In practice what will usually stop you is the operating system. Most of the major modern operating systems are designed to make a distinction between "readable",

问题 I tried to get the memory content of the address pointed by the function names [both abc() and main()], but both printf() inside a function give same output, although I dereference the address pointed by the function name in the second printf() inside each function. Why is that? Why the memory addresses are printed by *(abc) and *(main) instead of the contents? #include<stdio.h> void abc(){ printf("\n%p \n ", abc); printf("\n%#x\n ",*(abc)); } void main(){ abc(); printf("\n%p \n ", main);

问题 Ive been learning about lambdas and function pointers lately and wanted to use them in a simple callback system. The map that stores an event and all callbacks that should be called when it gets triggered looks like this: std::unordered_map< sf::Event::EventType , std::vector< Callback > > eventMap; . I defined Callback this way typedef void(*Callback)(sf::Event const&); . My registerEvent() function takes an event and a Callback as arguments. registerEvent() can then be called this way:

问题 Let's start with this playground example Example 1 import UIKit internal final class TestClass1 { var testVar: Int = 1 internal init() { print("TestClass1 init is called!") } deinit { print("TestClass1 deinit is called!") } internal func func1() { print("func1 is called!") } } internal final class TestClass2 { init() { let testClass1: TestClass1 = TestClass1() testClass1.testVar = 10 } } var testClass2: TestClass2 = TestClass2() Output TestClass1 init is called! TestClass1 deinit is called!

问题 I'd like to set up a function pointer as a member of a class that is a pointer to another function in the same class. The reasons why I'm doing this are complicated. In this example, I would like the output to be "1" class A { public: int f(); int (*x)(); } int A::f() { return 1; } int main() { A a; a.x = a.f; printf("%d\n",a.x()) } But this fails at compiling. Why? 回答1: The syntax is wrong. A member pointer is a different type category from a ordinary pointer. The member pointer will have to

问题 I'd like to set up a function pointer as a member of a class that is a pointer to another function in the same class. The reasons why I'm doing this are complicated. In this example, I would like the output to be "1" class A { public: int f(); int (*x)(); } int A::f() { return 1; } int main() { A a; a.x = a.f; printf("%d\n",a.x()) } But this fails at compiling. Why? 回答1: The syntax is wrong. A member pointer is a different type category from a ordinary pointer. The member pointer will have to

问题 I have this typedef to define a function pointer. typedef Script*(*CreateObjectFn)(TiXmlElement* node); I've created a generic container for my purpose that acts like a map. It's called Dictionary, so I've created a Dictionary of CreateObjectFn inside a class like this: class ScriptBank { public: ~ScriptBank(); static Dictionary<CreateObjectFn>& getInstance() { static Dictionary<CreateObjectFn>& registry = m_registry; return registry; } private: static Dictionary<CreateObjectFn> m_registry;

问题 Lyrics: I try to implement a task pool over MPI. So I need some kind of RPC but one that would work between different parts of my program, meaning processor A wants processor B to call function C with argument D. We can not pass pointers to functions between processes like we do with threads, so we need some wrapper container to hold our function pointers at each process instance. All inside one source file\one program... So I started wondering about How to store functional objects with