8.2

Collections

• Types of Collections

  • Set

    • Elements cannot be repeated

    • Elements are unordered

  • Multi-set

    • Elements can be repeated

    • Elements are unordered

  • List

    • Elements can be repeated

    • Elements are ordered

  • Array

    • An indexed list of elements

    • Each element can be accessed using a numeric index

Enumerated Types (Enum) & Set Values

• Base Type

  • Consists of character strings

  • Each Enum value must contain exactly one element

  • Each SET value may contain zero, one, or many elements

• Example of a Set:

  • SET(apple, banana, orange)

• Characteristics of SET:

  • Can represent an empty set (no elements)

  • Not the same as a null value

  • Represented as a series of bits, where each bit corresponds to a specific element

    • If a bit is 1, the corresponding element is included

    • If a bit is 0, the corresponding element is excluded

  • A base type can have at most 1 enumeration

Memory Representation

• A SET value can require a maximum of 64 bits (elements) of storage

  • Each bit represents inclusion/exclusion of elements

Array Types

• An array is defined using brackets to indicate size

  • Example: INTEGER [4] means an array consisting of 4 integers

• Integer Arrays

  • Defined as INTEGER ARRAY [4]

• Array values can be initialized using braces:

  • Example: {2, 5, 11.63} represents individual array values

• Accessing Array Elements

  • Array elements can be accessed by index (e.g., array[2] selects the 2nd element)

• Multi-dimensional Arrays

  • Specified using nested braces

  • Example: {{2, 5}, {6, 45}} represents a 2x2 multi-dimensional array

Additional Concepts

• Use of commas to separate values within braces

• Brackets may also specify multidimensionality by using multiple pairs of brackets

• Array notation is crucial for data structure representation and manipulation in programming.