C - Errors when trying to make a hashtable - c

Question

I'm working on a hash table that stores strings in linked lists so I can avoid collisions. However, I'm getting two errors that I'm not sure how to fix. The first error I am getting is in the line that says NewT->Table[i] == NULL;. It's saying warning: statement with no effects [-Wunused-value].
The second error I'm getting is in the same function. The error is in the line return NewT and the error is warning: return from incompatible pointer type[enabled by default]. I've been staring at this for awhile and I can't see where there is an unused value and I have no idea what the return error means even after a bit of research. Can someone explain these to me and help me fix them?
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define HASH_MULTIPLIER 65599
/*Structures*/
typedef struct List_T
{
char *str;
int count;
struct List_T *next;
} ListT;
typedef struct Hash_T
{
int htsize;
ListT **Table;
} HashT;
/*Prototypes*/
unsigned int hash(const char *str);
HashT **ht_create(void);
int htsize;
int main(int argc, char *argv[])
{
if (argc <= 1)
{
printf("Please declare a table size");
return 1;
}
htsize = atoi(argv[1]);
return 0;
}
unsigned int hash(const char *str)
{
int i;
unsigned int h = 0U;
for (i = 0; str[i] != '\0'; i++)
h = h * HASH_MULTIPLIER + (unsigned char) str[i];
return h % htsize;
}
HashT **ht_create(void)
{
HashT *NewT;
int i;
if (htsize < 1) //invalid size for
{
fprintf(stderr,"Invalid Size for table");
exit(0);
}
if ((NewT = malloc(sizeof(HashT))) == NULL)
{
fprintf(stderr,"Invalid size for table");
exit(0);
}
if ((NewT->Table = malloc(sizeof(ListT *) * htsize)) == NULL)
{
fprintf(stderr,"Invalid size for table");
exit(0);
}
for (i = 0; i<htsize; i++)
{
NewT->Table[i] == NULL;
}
NewT->htsize = htsize;
return NewT;
}

Answer 1

The first error I am getting is in the line that says NewT->Table[i]
== NULL;. It's saying warning: statement with no effects [-Wunused-value].
This error shows up because the code is making a comparison and not an assignment. The value returned by the comparison (is Table[i] null?) is itself not assigned to anything else, which means it's unused.
Keep a single = operator instead of the doubled == to make sure you're actually assigning instead of comparing.
The second error I'm getting is in the same function. The error is in
the line return NewT and the error is warning: return from
incompatible pointer type[enabled by default].
Your function claims to be returning a pointer to a pointer to HashT, or HashT **, but you end up returning a pointer to HashT, or HashT * instead, which is the type of your NewT variable.
Your function's signature should use a single * instead of two.