Question

I have a problem understanding this structure , would love to get a clear explanation.

typedef struct exp{
   int x;
   struct exp *parent;
   struct exp **children;
}

what does it mean the parent and the children ?
“parent” is an array of this structure?
and what is the meaning of the children ? it’s an array of arrays?!
I really can’t understand..

and last thing, If I’m adding an element , it becomes a specific child of some parent, how can I reach all the children of a parent? shouldn’t it be a structure “List” (using next etc .. ? )?

thank you!!

Answer 1

This image shows a possible scenario:

It was obtained using this code and DDD

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

struct exp{
    int x;
    struct exp *parent;
    struct exp **children;
};

int main ()
{
    struct exp *x = calloc(1, sizeof(x[0]));
    x->x = 42;
    x->parent = calloc(1, sizeof(x[0]));
    x->children = calloc(5, sizeof(x->children[0]));
    x->children[0] = calloc(1, sizeof(x[0]));
    x->children[2] = calloc(1, sizeof(x[0]));
    x->children[3] = calloc(1, sizeof(x[0]));
    x->children[4] = calloc(1, sizeof(x[0]));
    return 0;
}

Basically, the children field is a vector of pointers to struct exp. You decide how many elements to put there and the other things.

PS: Code is only a demo, it has not quite a good quality.