Hashtabelle mit Verkettung

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 31 // prime number for size of array
#define h(x) (x % m) //h(x) = x mod m

// Node for List
typedef struct Node{
    int val;
    struct Node *next;
}Node;

//function's declaration
Node *fill_table(Node *table, int table_range, int number);
Node *insert(Node *table, int hash_index, int val);
Node *del(Node *table,int table_range,int val);
void print_table(Node *table, int table_range);
void search_table(Node *table, int table_range, int val);

int main(){
    Node *table; // hashtable
    int n, i, j, choice, search;
    int hash_num, val;

    // allocate table
    table = (Node*) malloc(N*sizeof(Node));
    //make table "heads" NULL
    for(i = 0; i < N; i++){
        table[i].next = NULL;
    }

    printf("--h(x) = xmod%d--\n",N);
    printf("\n\n");

    while(1){
        printf("1.Insert random numbers\n");
        printf("2.Delete a number\n");
    printf("3.Search a number\n");
    printf("4.Show Hash Table\n");
    printf("0.Exit Programm\n");
    printf("\n--------\n");
    printf("Choice: ");
    scanf("%d",&choice);

    switch(choice){
        case 0: return;
        case 1:
            // insert random numbers
            printf("Lot to insert: ");
            scanf("%d", &n);
            table = fill_table(table, N, n);
            printf("Filled HashTable with %d random values\n", n);
            printf("\n--------\n");
            break;
        case 2:
            // delete a number
            printf("Give a number: ");
            scanf("%d",&search);
            table = del(table, N, search);
            printf("\n--------\n");
            break;
        case 3:
            // search for a number
            printf("Give a number: ");
            scanf("%d",&search);
            search_table(table, N, search);
            printf("\n--------\n");
            break;
        case 4:
            //print hashtable
            printf("-HASHTABLE-\n\n");
            print_table(table, N);
            printf("\n--------\n");
            break;
        }
    }
    return 0;
}

// FUNCTIONS
Node *fill_table(Node *table, int table_range, int number){
    int i;
    int num;
    for(i=0; i<number; i++){
    num = rand()%10000; // random number from 0 to 9999
    table = insert(table, num % table_range, num);
    }
    return table;
}

void print_table(Node *table, int table_range){
    int i;
    Node* cur;
    for(i = 0; i < table_range; i++){ // for each list
    if(table[i].next == NULL){ // if empty
                printf("Table[%d] is empty!\n", i);
        continue;
    }
    cur = table[i].next;
    printf("Table[%d]", i);
    while(cur!=NULL){ // else print all the values
        printf("->%d",cur->val);
        cur=cur->next; //cur=cur+1;
    }
    printf("\n");
    }
}

Node *insert(Node *table, int hash_index, int val){
    Node *nn, *cur;

    nn = (Node*)malloc(sizeof(Node));
    nn->val=val;
    nn->next=NULL;

    if(table[hash_index].next == NULL){
    table[hash_index].next = nn;
    return table;
    }

    cur = table[hash_index].next;
    while(cur->next != NULL){
    cur=cur->next; //cur=cur+1;
    }
    cur->next = nn;
    return table;
}

void search_table(Node *table, int table_range, int val){
    int index = val % table_range;
    Node *cur;

    if(table[index].next == NULL){ // if empty
        printf("Value %d not found cause Table[%d] is emtpy!\n", val,index);
                return;
    }

    cur = table[index].next;
    while(cur!=NULL){
    if(cur->val == val){
        printf("Value %d was found!\n", val);
        return;
    }
    cur = cur->next;
    }
    printf("Value %d not found in Hashtable!\n", val);
}

Node *del(Node *table, int table_range, int val){
    int index = val % table_range;
    Node *prev;

    if(table[index].next == NULL){ // if empty
    printf("Value %d not found cause Table[%d] is emtpy!\n", val,index);
    return table;
    }

    if(table[index].next->val == val){ // if first item
    printf("Value %d was found at table[%d] and Deleted!\n", val,index);
    table[index].next = table[index].next->next;
    return table;
    }

    prev = table[index].next;
    while(prev->next!=NULL){
    if(prev->next->val == val){
        prev->next = prev->next->next;
        printf("Value %d was found at table[%d] and Deleted!\n", val,index);
        return table;
    }
    prev = prev->next;
    }
    printf("Value %d was not found in Hashtable!\n", val);
    return table;
}