Question

I’ve been tinkering with some code in a effort to understand OOP using c.
I really like this style and want to use it. The code sample works great if another class creates an instance of FooOBJ.

How can FooOBJ reference itself to change its own variables?
Do I need to make a copy of foo in the constructor or something like that or am I wandering away from the right way to use this methodology?

struct fooobj {
    int privateint;
    char *privateString;

};



FooOBJ newFooOBJ(){
    FooOBJ foo=(FooOBJ)malloc(sizeof(struct fooobj));
    bzero(foo, sizeof(struct fooobj));
    return foo;
}

void setFooNumber(FooOBJ foo,int num){
    if(foo==NULL) return;  /* you may chose to debugprint something
                *instead
                */
    foo->privateint=num;
}



void setmyself(int val)
{
   //this->privateint = val 
}

Answer 1

Well, any function operating on an instance of your “class” will have to take a pointer to the instance. This happens automatically and implicitly in C++, but in C you’ll have to pass a “this” pointer everywhere.

What this means is that your setFooNumber has the right signature for a “member function”, whereas setmyself does not.