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Understanding and Using C Pointers by Richard M Reese

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Chapter 6. Pointers and Structures

Structures in C can represent data structure elements, such as the nodes of a linked list or tree. Pointers provide the glue that ties these elements together. Understanding the versatility supported by pointers for common data structures will facilitate your ability to create your own data structures. In this chapter, we will explore the fundamentals of structure memory allocation in C and the implementation of several common data structures.

Structures enhance the utility of collections such as arrays. To create an array of entities such as a color type with multiple fields without using a structure, it is necessary to declare an array for each field and keep each value for a field in the same index of each array. However, with a structure, we can declare a single array where each element is an instance of the structure.

This chapter expands on the pointer concepts learned so far. This includes the introduction of pointer notation as used with structures, a discussion of how memory is allocated for a structure, a technique for managing memory used by structures, and uses of function pointers.

We will start with a discussion of how memory is allocated for a structure. An understanding of this allocation will explain how various operations work. This is followed by the introduction of a technique to minimize the overhead of heap management.

The last section illustrates how to create a number of data structures using pointers. The linked list is discussed ...

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