Emulating OOP in C using Function Pointers

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Basic OOP in C:

#include <stdio.h>

void printfn()

{

       printf("!\n");

}

struct foo

{

       void (*go)( void );

};

void setup( struct foo *FOO )

{

       FOO->go = printfn;

}

int main()

{

       struct foo f;

       setup(&f);

       f.go();

       return 0;

}

Using a more complex class, such as Cat (using multiple input parameters, the code gets a bit messy):

#include <stdio.h>

struct cat

{

       int posx,posy;

       void (*MoveTo)(struct cat *c, int x, int y);

       void (*Meow)( void );

       void (*DisplayPos)( const  struct cat *c );

};

void _meow()

{

       printf("Meow! :3\n");

}

void _moveTo(struct cat *c, int x, int y)

{

       c->posx = x;

       c->posy = y;

}

void _displayPos( const struct cat *c )

{

       printf("I am at (%d,%d).\n",c->posx,c->posy);

}

void setup( struct cat *FOO )

{

       FOO->Meow = _meow;

       FOO->MoveTo = _moveTo;

       FOO->DisplayPos = _displayPos;

}

int main()

{

       struct cat Cat;

       setup(&Cat);

       Cat.Meow();

       Cat.MoveTo(&Cat,1,5);

       Cat.DisplayPos(&Cat);

       Cat.Meow();

       return 0;

}

It would be better if the code didn't use the 'OOP':

#include <stdio.h>

struct cat

{

       int posx,posy;

};

void Meow()

{

       printf("Meow! :3\n");

}

void MoveTo(struct cat *c, int x, int y)

{

       c->posx = x;

       c->posy = y;

}

void DisplayPos( const struct cat *c )

{

       printf("I am at (%d,%d).\n",c->posx,c->posy);

}

int main()

{

       struct cat Cat;

       Meow();

       MoveTo(&Cat,1,5);

       DisplayPos(&Cat);

       Meow();

       return 0;

}

 

 Thus this is a waste of time unfortunately :c

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