Function array with function pointer in C assign to member function in C++

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I am looking for a way to assign a c++ class member function to c function array
I am not sure the concept that I'm looking for exists

class test
{
int id;
bool testid(int id1)
 {
  if(id>id1)
     return true;
   else
     return false;
 }
};
test item1, item2;
typedef bool (*test2) (int id);
test2 item3[2] = {&item1.testid, &item2.testid};

I don't want to define test2 in this way

typedef bool (test::*test2) (int id);

Many thanks for your guides

What I have tried:

I tried

void f1_0(int j);
void f1_1(int j);
typedef void (*f2)(int j);
f2 temp[2] = {&f1_0,&f2_0}

it works

Posted 27-Nov-18 0:43am

saide_a

Updated 27-Nov-18 22:14pm

v3

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KarstenK · Answer 1 · 2018-11-27T01:17:00

Solution 1

The syntax isnt so fully correct but it should work. Read this function pointer example in the main function. (the other stuff isnt so useful for you)

What are the reasons for this weired construction?

Posted 27-Nov-18 1:17am

KarstenK

Comments

saide_a 27-Nov-18 7:35am

I have a fixed function from a third party and I should assign to that

saide_a 28-Nov-18 4:08am

I have edited my question please look at it

CPallini · Answer 2 · 2018-11-27T01:20:00

Solution 2

It exist (if I got you) the possibility to make an array of function pointers, e.g.

C

#include <stdio.h>

int inc(int i){ return i+1;}
int dec(int i){ return i-1;}

int main()
{
  int (*f[2])(int) = {inc,dec}; // array of function pointers

  int x = 5;
  printf("%d,%d,%d\n", x, f[0](x), f[1](x)); // call the functions assigned to the array items
  return 0;
}

Posted 27-Nov-18 1:20am

CPallini

Comments

saide_a 28-Nov-18 4:08am

I have edited my question please look at it

CPallini 28-Nov-18 4:52am

"I don't want to define test2 in this way"
But there is NO another way (and you have to pass the pointer to the object when calling the functions). At least it is so until we are able to understand what you are really trying to do.

saide_a 28-Nov-18 6:04am

I should make a fixed name function which its implementation is different for different instance( not a class instance). and the[fix name func] void(* function)(input) = &Myfucntion only work on none class method

CPallini 28-Nov-18 6:43am

Could you please elaborate? What is the scenario? Have you to expose a C++ function to a C library? Details are needed.

saide_a 28-Nov-18 6:52am

It is so hard to explain, I am using canopen of canfestival , it is written in C and I am trying to make each node generically