Problems with a dictionary implementation in c - c

Question

So, I've been trying to implement a dictionary using an array(still haven't written DiDelete function, not relevant right now), but two problems emerged, here's the code:
#include <stdio.h>
#include <stdlib.h>
#define MAX 1000
typedef int elementtype;
typedef struct{
int last;
elementtype elements[MAX];
}Dictionary;
void DiMakeNull(Dictionary *A)
{
(*A).last = -1;
}
int DiMember(elementtype x, Dictionary A)
{
int f,m,l;
f = 0;
l = A.last;
m = (f+l)/2;
while(f <= l )
{
if( A.elements[m] == x) return 1;
else if( A.elements[m] < x) f = m+1;
else l = m-1;
m = (f+l)/2;
}
return 0;
}
void DiInsert(elementtype x, Dictionary *A)
{
int i = 0,j;
elementtype temp;
while( ((*A).elements[i] < x) && ((*A).last >= i) )
{
i++;
}
for(j = i ; j <= (*A).last; j++)
{
(*A).elements[j+1] = (*A).elements[j];
}
(*A).elements[i] = x;
(*A).last++;
}
int DiEmpty(Dictionary A)
{
if(A.last == -1) return 1;
return 0;
}
void DiPrint(Dictionary A)
{
int i;
printf("Dict:\n");
for(i = 0; i <= A.last; i++)
printf("%d\n",A.elements[i]);
printf("End!");
}
Question 1: why does DiPrint not work? After giving a Dictionary with confirmed numbers in its' array of elements it prints out random numbers. It seems fairly simple, I don't understand what I've gotten wrong there!
Question 2: Why is it, that when a function is e.g.
void function(Dictionary *A)
can't I use the notation A->last, but insted I have to use (*A).last
Thanks in advance!
EDIT: main program looks like this:
#include <stdio.h>
#include <stdlib.h>
#include "atp_dictionary_pomocu_liste.c"
int main()
{
Dictionary A;
DiMakeNull(&A);
DiInsert(4,&A);
DiInsert(3,&A);
DiInsert(32,&A);
DiPrint(A);
return 0;
}

Answer 1

Well I will tell you how I debugged. I like my compiler so I compiled the code.
error: could not convert '& A' from 'Dictionary*' to 'Dictionary'
DiPrint(&A);
^
It said to me that I have type mismatch in DiPrint().
Then three changes and it worked.
void DiPrint(Dictionary* A)
{
int i;
printf("Dict:\n");
for(i = 0; i <= (*A).last; i++)
printf("%d\n",(*A).elements[i]);
printf("End!");
}
And also in answer to your question why do we need to derefence it before using? Because we passed the address of the structure. Unless we dereference it , we won't get the struct instance.
From the comment I again had to rollback the code, we need to pass the structure instance directly and so we did
DiPrint(A);
and
void DiPrint(Dictionary A)
{
int i;
printf("Dict:\n");
for(i = 0; i <= A.last; i++)
printf("%d\n",A.elements[i]);
printf("End!");
}
And this would work without those unary *'s because we are working directly on the structure instance.
Isn't A->last and (*A).last the same thing?
Yes they are. That's why when you call it DiPrint(&A) this function would also work.
void DiPrint(Dictionary* A)
{
int i;
printf("Dict:\n");
for(i = 0; i <= A->last; i++)
printf("%d\n",A->elements[i]);
printf("End!");
}

Answer 2

You have an error in your code; in DiPrint(Dictionary A), your function expects type Dictionary but not type Dictionary *, you need to modify this calling function part in your code, so it would be:
DiPrint(A);
Not
DiPrint(&A);
Or another solution is modifying your function to accept a pointer instead, so it would be:
void DiPrint(Dictionary* A)
{
int i;
printf("Dict:\n");
for(i = 0; i <= (*A).last; i++)
printf("%d\n",(*A).elements[i]);
printf("End!");
}