Registering a c++ callback method in a C code

Question

I have a c++ class and c code as well. Following is rough (logically the same) and minimalised code

// C++ class - Car.cpp
void Car :: initialise() 
{ 
  WheelT mWheel;   // WheelT is a struct in Wheel.c
  mWheel.run(wheelGotFlat);    // <---- I want to pass here the c++ callback method , so that if the             wheel goes flat , the callback should hit 
}
static void car :: wheelGotFlat()   // <--- callback method
{
}

// C code - Wheel.c

void checkStatus(callback aCb)
{
   // if wheel is flat 
   // ----- here I want to hit the callback method that was passed as argument to run()
}
void run(callback aCb)
{                      
    checkStatus(aCb);       
}

How to do this ??

The callback method has to be static. – Rakib May 05 '14 at 03:04 — Rakib, May 05 '14 at 03:04
yes..it is static..i have modified the code. – Subbu May 05 '14 at 03:06 — Subbu, May 05 '14 at 03:06
What are you struggling with? – David Heffernan May 05 '14 at 03:10 — David Heffernan, May 05 '14 at 03:10

score 0 · Answer 1 · edited May 23 '17 at 12:20

0

To make a C++ function callable from C, use extern "C" void foo(int) { ... }, for example. To make it call a member function, you'll have to make the callback a stub written in C++, but callable from C, that then calls the member function.

Note that using a static member function will often work, but is actually undefined behavior. See this for more details.

edited May 23 '17 at 12:20

Community

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answered May 05 '14 at 03:03

kec

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Registering a c++ callback method in a C code

1 Answers1