Page 21 - DCAP407_DATA_STRUCTURE

Data Structure

Complex numbers consists of a real part and an imaginary part and both parts
are represented by real numbers. Different operations like addition, subtraction,
multiplication, and division can be performed on complex numbers. As we do
not have a true data type for complex numbers, we implement them using an
ADT.

Thus, ADT can be considered as the mathematical model for data structures that have similar
semantics.

Did you know? Applying an ADT means providing one procedure or function for every abstract
operation. The ADT instances are illustrated by some concrete data structure that is
manipulated by those procedures, according to the ADT's specifications.
1.4.1 Abstract Data Type (ADT) Model
As shown in figure 1.8, there are two different parts of the ADT model - functions (public and private)
and data structures. Both, the functions and data structures are contained inside an ADT model and are
not part of the application program. Data structures are available to all the ADT functions when
required and a function may call any other function to accomplish its task. This shows that data
structures and functions are within the scope of each other. Data is entered, accessed, modified and
deleted through the external application programming interface. This interface can access only the
public functions. Every ADT operation has an algorithm to perform a specific task. The operation name
and parameters are available to the application, and they provide the interface to the application.
Simple structures are used to implement a program that completely controls a list.

Figure 1.8: ADT Model

ADT

Application Public Function Private Functions
Program

Data Structures
Arrays
Linked List

Record

It is not enough if you just encapsulate the structure in an ADT. It is also necessary that
multiple versions of the structure coexist.

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