Question

The line *array[cnt] = thing causes a seg fault and I don’t know why. Any ideas to fix this?

long *Load_File(char *Filename, int *Size)
{
    FILE *fp;

    if((fp = fopen(Filename,"r")) == NULL)
    {
        printf("Cannot open file.\n");
        exit(-1);
    }

    fscanf(fp,"%d",Size);

    int cnt = 0;
    int items = *Size;
    long * array[items];
    int thing;

    while (!feof(fp))
    {
        fscanf(fp,"%d",&thing);
        *array[cnt] = thing;
        cnt++;
    }

    fclose(fp);

    return *array;
}

Answer 1

long * array[items];

is declaring an array of pointers to long data type. But these pointers are not pointing to anything meaningful.

When you do

*array[cnt] = thing;

you are dereferencing the pointer which is incorrect since they dont point to anything meaningful.

You can dynamically allocate the memory for the array as:

long * array = (long*) malloc(size(long) * items);

and then do:

while (!feof(fp)) {
        fscanf(fp,"%d",&arr[cnt++]);
    }

and then return the array as:

return array;