最后标注的那几句怎么理解

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "ctype.h"
typedef char Datatype;
typedef struct node{
    struct node *tlink;
    int tag;
    union{
        struct node *hlink;
        Datatype value;
    }info;
}Crossnode,*Crosslist;
#define maxsize 30
#define defaultsize 50
void createlist();
void createlist(char *s, int &i, Crossnode* &h, char L1[], Crosslist L2[], int &k)
{
    Crossnode *p; char nam, ch;
    nam = ch; ch = s[i++];
    if (isupper(ch))
    {
        h = (Crossnode*)malloc(sizeof(Crossnode));
        h->tag = 2; nam = ch; ch = s[i++];
        if (ch == '(')
        {
            p = (Crossnode*)malloc(sizeof(Crossnode));
            p->tag = 0;
            h->info.hlink = p;
            L1[k] = nam; L2[k++] = p;
            if (s[i] == '#')
            {
                p->tlink = NULL;
                i++;
            }
            createlist(s, i, p->tlink, L1, L2, k);