Thread: Structures, code completed. Creating the comments

Hello


I have a sample of unexplained code snippet of which I am trying to make sense by writing the comments myself. In looking at it from above, it looks like a linked structure, sort of the stuff you would build in a tree menu or something like that, yet I dont quite visualize it. I dont know if this snippet is a beginner level, but it looks to me somewhat convoluted.

Thank you

Code:

#include <stdio.h>
#include <stdlib.h>
# define M 3

struct clas  //NO PROBLEM HERE
{
    char name[16];
    int key;
};


struct node
{
    int n; 
    struct node *p[M];  // ARRAY OF POINTERS TO STRUCTURES BUT UNCLEAR TO ME, 
//IS IT LIKE ONE OF THOSE TREE MENUS? A LINKED STRUCTURES BECAUSE THE POINTERS ARE POINTING TO ITS OWN STRUCTURE

    struct clas clsf[M-1] ;  // ALSO AN ARRAY OF POINTERS TO STRUCTURES, BUT THIS TIME POINTING 
//TO THE STRUCTURE "CLAS" THIS IS LIKE NESTLED STRUCTURES, RIGHT? Update: yes sorry, of course, no pointers here, 
};

main()
{
    int i;

    struct node *root; // THIS POINTER POINTING AT THE "SUBSTRUCTURE" CREATED ABOVE...


// OR ARE WE JUST GIVING IT A NAME TO ONE OF THE POINTERS
// THAT ARE PART OF THE ARRAY OF POINTERS CREATED ABOVE
    for(i=0;i<2;i++)
    {
        root = malloc(sizeof (struct node)); 
        printf("enter name \n");
        scanf("%s",root->clsf[i].name);
        printf("%s\n",root->clsf[i].name);
        printf("enter key\n");
        scanf("%d", &root->clsf[i].key);
        printf("%d",root->clsf[i].key);
    }
}

Code:

    struct clas clsf[M-1] ;  // ALSO AN ARRAY OF POINTERS TO STRUCTURES, BUT THIS TIME POINTING
//TO THE STRUCTURE "CLAS" THIS IS LIKE NESTLED STRUCTURES, RIGHT?

These are not pointers. These are actual structures. 'node' contains a number, three poitners to other nodes, and two structures of type 'clas'.

They make one root node, and allocate space for that. The problem with this example though, is that it overwrites 'root', losing the first entry. It should be checking to see if root is null, and if not, making the new node point to it, as not to lose it.


Quzah.

// ARRAY OF POINTERS TO STRUCTURES BUT UNCLEAR TO ME,
//IS IT LIKE ONE OF THOSE TREE MENUS? A LINKED STRUCTURES BECAUSE THE POINTERS ARE POINTING TO ITS OWN STRUCTURE

Obviously a linked list, it may be a form of tree, as you said, with left-mid-right for smaller-equal-greater values. Or is might be a ( in lack of a better word ) hierarchical linked list that points to the previous, next and child or parent nodes.

// ALSO AN ARRAY OF POINTERS TO STRUCTURES, BUT THIS TIME POINTING
//TO THE STRUCTURE "CLAS" THIS IS LIKE NESTLED STRUCTURES, RIGHT?

An array of structures, rather. I see no pointers there.

// THIS POINTER POINTING AT THE "SUBSTRUCTURE" CREATED ABOVE...
//I DONT SEE THE POINT, EXCUSE THE PUN

A linked list needs a referense point, something from where to start. That's obviously it's "root".

// WHY DYNAMIC ? HAVENT WE FIXED IT AT LENGTH 16 CHARS?

Humm, you need a tutorial on C's struct. Seriously!

Not writing all English text in upper case would be a bonus as well.

@Greaper: I believe the dynamic memory allocation to structure is meant because even if you set a maximum length for its members, that gives anyway variable needs of memory in the structure itself. I have been studying C for two weeks so far, I try the hardest I can. I appreciate your help.

@SALEM The reason I wrote it in upper case is because also for myself in my own laptop I do it like that, since in my programming environment it is written in soft gray and I can barely see it. However, here it remarks it in green, and makes it more visible, but I copied it and pasted from my own place. Somehow it helps me differentiate the comments more clearly from the code. Sorry if it visually looked annoying

> since in my programming environment it is written in soft gray and I can barely see it.
So your inability to choose a decent colour scheme translates into our eyesore.