This document defines and provides examples of common data types used in programming languages including integers, reals, strings, Booleans, and one-dimensional arrays. Integers store whole numbers, reals store decimal numbers, strings store alphanumeric text, Booleans store true/false values, and one-dimensional arrays store a series of elements of the same type with indexes. Examples of how each data type could be used in programs are also provided.
2. Data Types
Computer programs need to process and store data
Programming languages define different data types to
store different types of data
We are interested in the following data types:
Integer, Real, String, Boolean, One-Dimensional Arrays
and Records
3. Integer
An integer data type is used to store a whole number
An integer can be positive or negative and includes 0
e.g. 4, 1025, -27, 0, -911, 1
4. Real
A real data type is used to store a decimal number
A real can be positive or negative and includes 0
e.g. 22.1, -13.775, 0.00, -5.15, 102.4258
5. String
A string data type is used to represent alphanumeric
data (i.e. text)
e.g. "Hello World", "0131 334 9262",
"How are you today?", "ABC-DEF-%£$-123"
Most programming languages provide ways to
manipulate strings
e.g. get the string length, get the first character, get the
4th-6th characters, find the first space
6. Boolean
A boolean data type can only represent 2 values: true
or false.
Depending on the programming language true can also
be a 1 or yes, while false can be a 0 or no
7. One Dimensional Arrays
An array is a series of objects all of which are the same type
Each object in an array is called an array element
The index of the first array element is normally zero
Arrays are useful in programming because they can be used
with a loop
(eg count occurrences, linear search, find max/min)
8. One Dimensional Arrays
An example array of integers: The winning lottery balls
Uses:
Write a program to loop through checking a user’s
lottery numbers
9. One Dimensional Arrays
An example array of reals: Daily temperatures over a week
Uses:
Write a program to calculate the average daily
temperature in a week
10. One Dimensional Arrays
An example array of Strings: Pupil names
Uses:
Write a program to sort pupils into alphabetical order