Unexpected output while counting allocated memory in an array

Question

I'm working on a dynamic allocation project and I get a constant unexpected answer for a test case. The output consistently prints out 'test of size: 11' and I can't figure out why.

getSize() goes through all the values and adds to the count if it's not NULL (in practice, counts all the valid elements in the array).

I'm using getSize() as a fallback incase the var in ArrayList size does not output correctly. Also, the array's created using calloc() and referenced to test is wacky. If I do a for loop to print out all the values, it stops midway and crashes (in the case of array of size 25, it consistently stops after index 7.) However, if I printf the index if seg faults on with the loop, it works perfectly. Is the logic wrong, or do I have to flush something?

If I change the test case to where the size of array is bigger or larger, the same thing happens where there is a constant int printing out.

typedef struct ArrayList
{
    // We will store an array of strings (i.e., an array of char arrays)
    char **array;

    // Size of list (i.e., number of elements that have been added to the array)
int size;

    // Length of the array (i.e., the array's current maximum capacity)
    int capacity;

} ArrayList;

int main(void){
    struct ArrayList *test;
    test=createArrayList(25);
    int i=getSize(test);
    printf("test of size: %d", i);
    return 0;
}

//creates the array list and allocated memory for it
ArrayList *createArrayList(int length){
    struct ArrayList *r = malloc(sizeof(*r));
    if (r == NULL)//Returns null if malloc does not work
        return NULL;
    length=(length<DEFAULT_INIT_LEN) ? DEFAULT_INIT_LEN: length;//figures which value is         greater and keeps it
    r->array=calloc(sizeof(char), (length+1));
    if (r->array == NULL){//returns null if malloc does not work
            printf("error\n");
            return NULL;
    }
    r->size = 0;
    r->capacity = length;
    printf("Created new ArrayList of size %d.\n", length);
    return r;
}
//the function im having trouble with
int getSize(ArrayList *list){
    int i=0, count=0;//index variables
    if (list->array==NULL)
        return -1;
    for (i=0; i<(list->capacity-1); i++){//goes through all indexs of internal array and     conuts valid elements. this is where im having trouble specifically
        if (list->array[i]!=NULL)
            count++;
    }
    return count;
}

Answer 1

This is wrong:

r->array=calloc(sizeof(char), (length+1));

It should be sizeof(char *), since you're allocating space for an array of pointers to char. Or, even better, don't hardcode the type of the array elements at all, and use *r->array instead:

r->array = calloc(sizeof(*r->array), length+1);

It also feels a little weird that you allocate length+1 elements and then only go up to capacity-1 in getSize(). I think you just want length.

Answer 2

It seems to me that this part tries to index list elements that do not exist:

for (i = 0; i < (list->capacity - 1); i++)
{
    if(list->array[i] != NULL)
        count++;
}

Maybe this is better for what you're trying to accomplish:

while (list->array[i++] != NULL)
{
    count++;
}