Data Types

Data Types

What is a data type?

• 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

What is 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>int_value = 5<br><br>real_value = float(int_value)<br>	5.0
From Real to Integer	python<br>real_value = 5.7<br><br>int_value = int(real_value)<br>	5
From String to Integer	python<br>int_str = "10"<br><br>int_value = int(int_str)<br>	10
From Integer to String	python<br>value = 5<br><br>str_value = str(value)<br>	"5"
From Boolean to String	python<br>bool_val = True<br><br>str_val = str(bool_val)<br>	"True"
From String to Boolean	python<br>bool_str = "True"<br><br>bool_val = bool(bool_str)<br>	True