Question

i am having objective c class, which i have a C function in it.
in that C function i want to call to ANOTHER c function in another class.

in the first class C function , i do this :

  HelloWorldLayer *ran;
  ran=[[HelloWorldLayer alloc] init];
  [ran showDigital:BinaryWord];

when HelloWorldLayer is the other class, which have the C function :

void showDigital( int word[4])

and it declared also in the HelloWorldLayer.h .

in the first class, when i am trying to call the other function it says that showDigital function is not found.

is it has to do with the fact that its a C function ?

thanks.

Answer 1

First of all, the C function is not in the other class, it is merely in the same file as the other class. Objective-C classes have methods not functions.

So you can call your C function from anywhere provided you have an extern declaration of it. e.g. in HelloWorldLayer.h

extern void showDigital(int* word);

If you really want the function to be associated with instances of your class, you need to make it an Objective-C method. You can have that method be a thin wrapper for the original function if you like:

-(void) showDigital: (int*) word
{
    showDigital(word);
}

If you want to pretend that your C function is part of an object, you’ll need to add the receiver object as a parameter. You still won’t be able to access private instance variables directly though.

void showDigital(id self, int* word)
{
    [self foobar];
}