function-pointers

What is the best way to call a specified function based on user input except from series of if and strcmp ? For example: p 2 2 -> call func_p(2, 2) a 8 -> call func_a(7) m -> call func_m(void) I know it's easy and elegant to make a lookup table consisting of function pointers with the same prototype but how about different prototypes? I thought about using ... in a prototype but I don't know if it's a good solution. Define all the functions so they take a single array argument. Comment from Barmar Unifying all functions to the same prototype is exactly what one normally does in this case,

I've been experimenting with function pointers and found the behavior of the following program rather misterious: void foo(int(*p)()) { std::cout << p << std::endl; } int alwaysReturns6() { return 6; } int main() { foo(alwaysReturns6); return 0; } The above code prints the number '1' on the screen. I know I should access the function pointer like this: p() (and then 6 gets printed), but I still don't get what the plain p or *p means when used in the foo function. std::cout << p << std::endl; here an overload of operator<< which accepts a bool is picked up: basic_ostream& operator<<( bool value

How do I create a metafunction that takes any kind of function pointer? In the code below, how do I get rid of "decltype(&f)" ? template <class FuncType, FuncType functionPointer> void runFunc() { functionPointer(); } runFunc<decltype(&f),f>(); I don't want to have to specify the type of f seperately; the information is already there in f. I'd prefer not to resort to defines to solve this. This is basically the templated function type idiom applied to meta-programming; I don't want to know the type of f, but whatever I get in apparently allows me to call operator() on it. Stuff I've tried:

I've managed to implement and test my function wrapper implementation, however, the interface isn't as nice as it should be: template < typename F, F* f > void register_function( const char* name ) { int (*lf) (lua_State *) = function_wrapper< F, f >; register_native_function( lf, name ); } While this works as expected, the usage requires to explicit template parameters: register_function< decltype(hello), &hello >( "hello" ); Obviously the first parameter could be deduced from the first one, so ideally I'd like to just have register_function< &hello >( "hello" ); Is it possible? Is there a

I am trying to write a class template and internally it use a C function (implementation of BFGS optimization, provided by the R environment) with the following interface: void vmmin(int n, double *x, double *Fmin, optimfn fn, optimgr gr, ... , void *ex, ... ); where fn and gr are function pointers of type typedef double optimfn(int n, double *par, void *ex); and typedef void optimgr(int n, double *par, double *gr, void *ex); respectively. My C++ class template looks like this: template <typename T> class optim { public: // ... void minimize(T& func, arma::vec &dpar, void *ex) { std::function

I am trying to implement my own is_member_function_pointer and I'm having trouble with it. namespace __implementation { // integral_constant template<typename T, T v> struct integral_constant { static constexpr T result = v; typedef integral_constant<T,v> type; constexpr operator T() { return result; } }; // true_type typedef integral_constant<bool, true> true_type; // false_type typedef integral_constant<bool, false> false_type; // remove_const template<typename T> struct remove_const { typedef T type; }; template<typename T> struct remove_const<const T> { typedef T type; }; // remove

I have the implemented a binary search tree but I also want to make it generic. The code is the following: typedef struct treeNode { int data; struct treeNode *left; struct treeNode *right; } treeNode; and the functions: treeNode* FindMin(treeNode *node) { if(node==NULL) { /* There is no element in the tree */ return NULL; } if(node->left) /* Go to the left sub tree to find the min element */ return FindMin(node->left); else return node; } treeNode * Insert(treeNode *node,int data) { if(node==NULL) { treeNode *temp; temp = (treeNode *)malloc(sizeof(treeNode)); temp -> data = data; temp -> left