Hash Table - Sort Structure with qsort - c

Question

Alright sorry for creating another question but the last one got overwhelmed and chaotic.
So I'm making a hash table which inserts words from a file (tokens) and after I have inserted them I need to sort them. The program template was given, the only functions that weren't complete were : insert_ht() , clear_ht() and compare. Even though I've done tons of search about qsort with compare, the program doesn't sort the frequencies (number of times each word was inserted) . I want em sorted from the highest to lowest.
Here is the code : "note that i shouldn't change any function except insert_ht() , clear_ht() and compare
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#define HTABLE_SIZ 1001
#define MAX_LINE_SIZ 1024
/* Hash Table */
typedef struct node* link;
struct node { char *token; int freq; link next; };
link htable[HTABLE_SIZ] = { NULL }; /* Table of lists (#buckets) */
int size = 0; /* Size (number of elements) of hash table */
unsigned int hash (char *tok );
void insert_ht (char *data);
void clear_ht ( );
void print_ht ( );
void Process(FILE *fp);
int main(int argc, char *argv[])
{
int i;
FILE *fp;
printf("prin tin for \n");
for (i=1; i < argc; i++)
{
printf("prin tin fopen \n");
fp = fopen(argv[i],"r");
if (NULL == fp)
{
fprintf(stderr,"Problem opening file: %s\n",argv[i]);
continue;
}
printf("prin tin process \n");
Process(fp);
fclose(fp);
}
print_ht();
//clear_ht();
return 0;
}
void Process(FILE *fp)
{
const char *seperators = " ?!'\";,.:+-*&%(){}[]<>\\\t\n";
char line[MAX_LINE_SIZ];
char *s;
while((fgets(line,MAX_LINE_SIZ, fp)) != NULL)
{
for (s=strtok(line,seperators); s; s=strtok(NULL,seperators)){
printf("prin tin insert %s \n",s);
insert_ht(s);
}
}
}
/* Hash Function */
unsigned int hash(char *tok)
{
printf("bike stin hash \n");
unsigned int hv = 0;
while (*tok)
hv = (hv << 4) | toupper(*tok++);
printf("VGAINEIIIIIIIIIIIIII %d \n",hv);
return hv % HTABLE_SIZ;
}
void insert_ht(char *token)
{
printf("bike stin insert %s \n",token);
unsigned int hashval = hash(token);
struct node *new_list;
if (htable[hashval]==NULL){
printf("mesa stin prwti if %u %s \n",hashval,token);
//token = strdup(token);
new_list = malloc(sizeof(link));
new_list->token = strdup(token) ;
new_list->freq = 1;
new_list->next = htable[hashval];
htable[hashval] = new_list;
size++;
}else {
htable[hashval]->freq++;
}
printf("ta evale epitixws \n");
}
void clear_ht()
{
int i;
for(i=0; i<HTABLE_SIZ; i++) {
while(htable[i]->token!=NULL) {
htable[i]->token=NULL;
htable[i]->freq=NULL;
free(htable[i]);
}
}
}
int compare(const void *elem1, const void *elem2)
{
const struct node *p1 = elem1;
const struct node *p2 = elem2;
if (p1->freq > p2->freq)
return(+1);
else if (p1->freq < p2->freq)
return(-1);
else
return(0);
}
void print_ht()
{
int i, j=0;
link l, *vector = (link*) malloc(sizeof(link)*size);
for (i=0; i < HTABLE_SIZ; i++)
for (l=htable[i]; l; l=l->next)
vector[j++] = l;
qsort(vector,size,sizeof(link),compare);
for (i=0; i < size; i++)
printf("%-50s\t%7d\n",vector[i]->token,vector[i]->freq);
free(vector);
}

Answer 1

Ι found the solution. Apparently for some reason my compare function was wrong.
I still haven't figured out why but here is the correct one, hopefully someone else will find this post helpful!
int compare(const void *elem1, const void *elem2)
{
return (*(link*)elem2)->freq - (*(link*)elem1)->freq;
}