I would like to have a function called "get_example_by_id" which takes in an int l and "returns" int a, b and two function pointers f and J. My initial take would be: int a, b; double (*f) (double), (*J) (double, double); get_example_by_id(l, &a, &b, &f, &J); Later on, I need f and J to be… Read More receiving function pointers and storing them in variables in standard c

I’ve declared the following function in C++ void setCellInfo (CELL_MESH* target, int Global_ID, int node0,vector<NODE_MESH *>* NodeStore, vector<CELL_MESH *>* CellStore) { CellStore->push_back(target); //No Errors target->Global_ID = Global_ID; //No Errors if (node0 != 0) { target->node[0] = NodeStore[vector<NODE_MESH *>::size_type(node0)]->ID; //ERROR 1 target->node_pointers[0] = NodeStore[vector<NODE_MESH *>::size_type(node0)]; //ERROR 2 } } ERROR1: Gives me a "No member named… Read More Passing pointers of vectors with structures C++

I have this piece of code: int foo(){ return 0;} int main() { int (*float_function)(float) = foo; } Compile using x86-64 gcc 12.2, with -Wall, it produces the warning (Link): warning: initialization of ‘int (*)(float)’ from incompatible pointer type ‘int (*)()’ [-Wincompatible-pointer-types] but when I change from float to double (Link): int foo(){ return 0;}… Read More Why does having a int* (float) point to a int() have a warning, but int* (double) don't?

When I initialize function pointers in one take, like below, it does not work. ptr[3]={add, subtract, multiply}; This gives: [Error] expected expression before ‘{‘ token However, one-by-one initialization works. Why is this? //array of function pointers #include<stdio.h> void add(int a, int b){ printf("%d\n", a+b); } void subtract(int a, int b){ printf("%d\n", a-b); } void multiply(int… Read More Do I have to initialize function pointers one by one?

In C++ you can have methods/class functions but in C that is not possible. However it is common for some people to use a constructor function in C and then assign function addresses to function pointers within the struct. For example: #include <stdio.h> void func_wave() { printf("Wave\n"); } void func_handshake() { printf("Handshake\n"); } typedef struct… Read More Implementing OOP in C vs OOP in C++

I have a member function pointer inside of my MethodPtr class. That’s public and is declared like this: void (Method::*func)() = nullptr; It’s giving me multiple errors and I’m unsure why. These errors are ‘func’: unknown override specifier ‘Method’: is not a class or namespace name ‘methodptr’: unkown override specifier missing type specifier syntax error:… Read More Member Function Pointer Giving multiple errors

There is an objects with field double (A :: *ptrToFunc)(); Object B has got A; Can’t use it in objects B class Foo { public: double (Foo :: *ptrToFunc)(); private: double func1(); double func2(); public: Foo() : ptrToFunc{ &Foo::func1 } {} } class B { public: Foo obj; double countVal() { return (obj.*ptrToFunc)(); // use… Read More Why I can't use pointer to a function

I have a tricky problem and I’m working on it for several hours but can’t find a cause and solution of it. Hope someone help me. I have to demonstrate function being called inside another function( pls see the comment in seminar.cpp) Below are the files ( I have separated it into header and code… Read More std::function Error : error: static assertion failed: Wrong number of arguments for pointer-to-member?

I’m writing a program in C which has a container (linear linked list) which contains char arrays as its data. I’m required to write a function firstItem(container* containerADT) which returns the the struct variable top. I’ve tried writing the firstItem function many times in many different ways and I keep getting the same error. My… Read More I keep getting an error when working with pointers in C

So I need to write some code that performs partial integration. I have a numerical integrator schematically represented by double integrate(double (*func)(double)); and suppose it works properly, i.e. for a function double f(double x), integrate(f) gives the right result. What I have instead, however, are functions that look like double f(double x, double y); and… Read More Creating function pointers in C with arguments