Primitive Data Types

Primitive Data Types

What are Data Types?

• A data type is a classification of data into groups according to the kind of data they represent

• Computers use different data types to represent different types of data in a program

• The basic data types include:

  • Integer: used to represent whole numbers, either positive or negative

    • Examples: 10, -5, 0

  • Real: used to represent numbers with a fractional part, either positive or negative

    • Examples: 3.14, -2.5, 0.0

  • Char: used to represent a single character such as a letter, digit or symbol

    • Examples: ‘a’, ‘B’, ‘5’, ’$’

  • String: used to represent a sequence of characters

    • Examples: “Hello World”, “1234”, ”@#$%”

  • Boolean: used to represent true or false values

    • Examples: True, False

• It is important to choose the correct data type for a given situation to ensure accuracy and efficiency in the program

Casting

• Casting is when you convert one data type to another data type

• When a user enters data into a program, this will more than likely be in a string format

• It’s essential to convert some of this string data to a numerical format where possible

• For example, you may want to perform calculations on age-related data to determine if someone is eligible to vote

• Some programming languages can’t execute numerical comparisons on text data, making this transformation crucial

• For example if you had “12” stored as a string and you wanted to know if this value was below 20

• Therefore, the string value of “12” will need to be cast as an integer to allow the comparison to take place

Python example

int_value = int("123") // converts the string "123" to 123
float_value = float("3.14") // converts the string "3.14" to 3.14

Java example

int intValue = Integer.parseInt("123"); // converts the string "123" to 123
double doubleValue = Double.parseDouble("3.14"); // converts the string "3.14" to 3.14

Casting between data types

Conversion	Example	Output
From Integer to Real	python<br>real_value = float(int_value)<br>	5.0
From Real to Integer	python<br>int_value = int(real_value)<br>	5
From String to Integer	python<br>int_value = int(int_str)<br>	10
From Integer to String	python<br>str_value = str(value)<br>	"5"
From Boolean to String	python<br>str_val = str(bool_val)<br>	"True"
From String to Boolean	python<br>bool_val = bool(bool_str)<br>	True

Worked Example

You are tasked with designing a program for a bookstore.

The program should be able to store each piece of information given in table.

Book Detail	Recommended Data Type

Complete the table by identifying a suitable data type for each piece of information in the table.

5 marks

Answer that gets full marks

Book Detail	Recommended Data Type
The book’s title	String
The number of pages the book has	Integer
The price of the book	Float
Whether the book is currently in stock or not	Boolean
The average rating given by customers which ranges from 1 to 5	Float