The Microprocessor

CHAPTER 15Extended Data Types

About this chapter

In the previous two chapters, we looked at how function calls and basic data types are implemented in C. We will continue our discussion in this chapter and take a look at how arrays, structures and pointers are implemented.

What do we learn?

• How is an array implemented in C?
• How is a structure stored and accessed from memory?
• What are pointers, and how are they implemented in C?
• How does the program access data element in an array and at a pointer?
• How are arithmetic operations performed on pointers?
• What are the pitfalls to be careful about while using the pointers?

As in the previous chapter, we will use a programming approach and learn by running small programs on the processor.

15.1 ARRAYS

An array is a block of memory containing elements of the same type. We access each element in the array using its index. An array is defined specifying the number of elements in the array.

int a[100];

Here, a is an array of 100 integers. We can access its elements using its index, for example, a[17]. Please note that the index starts from 0, so a[17] is actually the 18th element in the array.

The base address of the array is the same as the address of the first element, referred using the name of the array itself. In the above example, we say the base address of the array is a, which is the address of its first element, a[0].

The address of the i^th element in the array can be computed as base address + i times the size ...