3. Pointers and Arrays
In C, there is a strong relationship between pointers and arrays, strong enough that pointers and arrays    should be discussed simultaneously.
Primitive arrays implemented in C using pointer to block of contiguous memory.
Define an array size of 10, that is a block of 10 consecutive objects named a[0], a[1], ..., a[9].
int a[10], x;
int *pa;
pa = &a[0];  // pa contains the address of a[0]
pa = a;        // Since the name of an array is a synonym
                 // for the location of the initial element
x = *pa;      // will copy the contents of a[0] into x
The sizeof() Operator
For primitive types/variables, size of type in bytes:
sizeof(char);            // 1
sizeof(double);        // 8 (64-bit OS)
For primitive arrays, size of array in bytes:Array length:
int arr[8];                // sizeof(arr) == 32 (64-bit OS)
long arr [5];            // sizeof(arr) == 40 (64-bit OS)
Array length
/* needs to be on one line when implemented */
#define array _length(arr) \
( sizeof(arr) == 0? \
0 : sizeof(arr)/ sizeof((arr)[0]))
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