C encapsulation example

example.c

/* Example usage */

#include <stdlib.h>
#include <stdio.h>

#include "foo.h"

void main(void) 
{
    Foo my_foo = new_foo();
    
    foo_increment(my_foo);
    foo_increment(my_foo);
    
    printf("my_foo->count = %d \n", foo_getcount(my_foo));
    
    foo_increment(my_foo);
    foo_say(my_foo);
    
}

foo.c

/* An actual implementation of foo */

#include "foo.h"

#include <stdlib.h>
#include <stdio.h>

struct foo {
    /* Foo's member variables */
    int count;
};

/* Constructor implementation */
void foo_init(Foo self)
{
    self->count = 0;
}

Foo new_foo()
{
    Foo self = (struct foo*) calloc(1, sizeof(struct foo));
    
    foo_init(self);
    
    return self;
}

/* Method implementations */
void foo_increment(Foo self)
{
    self->count = self->count + 1;
}

int foo_getcount(Foo self) {
    return self->count;
}

void foo_say(Foo self)
{
    printf("%s", "I'm a foo! Count = %d \n", foo_getcount(self));
}

foo.h

/* The "public interface" to class Foo */

struct foo;
typedef struct foo* Foo;

/* Constructor */
void foo_init(Foo self);
Foo new_foo();

/* Some methods */
void foo_increment(Foo self);
int foo_getcount(Foo self);

void foo_say(Foo self);