Sequential Data Structures

So far you’ve worked with individual variables. But when a program needs to handle many related pieces of data, a better way of organizing them is needed.

That’s where handling sequential data structures appears.

In this lesson you will learn:

• what a sequential data structure is
• why individual variables aren’t enough
• what it means for data to be ordered in a sequence
• what operations are commonly done on a sequence

Key idea: a sequential structure allows thinking of several pieces of data as an ordered set and not as isolated variables.

What is a sequential data structure?

A sequential data structure is an organization where elements are arranged one after another following an order.

For example, a sequence of grades might look like:

8, 6, 10, 7, 9

Here you don’t think about five separate variables, but about an ordered collection of five values.

Why aren’t individual variables enough?

Look at this example:

int grade1 = 8;
int grade2 = 6;
int grade3 = 10;
int grade4 = 7;
int grade5 = 9;

This can work for very few pieces of data, but it has problems:

• it’s hard to traverse them in an orderly way
• it’s hard to apply the same operation to all of them
• it doesn’t scale well if the amount increases
• it makes the program rigid and messy

Relationship between sequence and operations

When data is organized sequentially, very important operations appear:

• traversal: visiting each element one by one
• search: finding a value within the sequence
• insertion: adding a new element
• update: changing an existing element

Conceptual example

Suppose you have the ages of four people:

20, 18, 25, 19

The program can ask questions like:

• what is the first age?
• what is the third?
• is age 25 in the sequence?
• what is the largest?

What sequential structures will you study?

In this part of the course you will mainly work with:

• arrays
• strings
• lists
• stacks
• queues

Not all work the same, but they all organize data sequentially.

Summary

• a sequential structure organizes several pieces of data following an order
• it allows treating a collection as a set
• it facilitates traversal, search, and insertion
• it’s the foundation for understanding arrays, strings, and various dynamic structures

Final idea

When you go from individual variables to sequential structures, your program starts handling real data and not just isolated values.