1.1 Programming Basics

• Memory: the location where instructions and data are stored on the computer
• Algorithm: a sequence of steps that can be followed to complete task and that always terminates
• Syntax: the rules of how words are used within a given language
• Memory address: a specific location where instructions or data are stored
• Assignment: the process of giving a value to a variable or constant
• Constant: an item of data whose value does not change
• Variable: an item of data whose value could change while the program is being run
• Debug: the process of finding and correcting errors in programs
• Declaration: the process of defining variables and constants in terms of their names and data types
• Data type: determines what sort of data are being stored and how it will be handled by the program
• Integer: any whole positive or negative number including zero
• Pointer: a data item that identifies a particular element in a data structure - normally the front or rear
• Array: a set of related data items stored under a single identifier. Can work on one or more dimensions
• Element: a single value within a set or list - also called a member
• Record: one line of a text file

Naming and Storing Data

• The data are stored in memory along with the instructions
• Using meaningful names will help you when they are trying to trace bugs and it also allows other programmers to follow the code more easily
• The process of giving data values is called ‘assignment’
• A simplified visualisation of how data is handled

Memory Addresses	1000	1001	1002
Variable	Number1	Number2	Answer
Data	2	3	5

• There will be millions of memory addresses, only three are shown in this diagram

Constants and Variables

• Data are stored either as a constant or a variable
• The name given to a constant should be self-explanatory
• Meaningful names make the code easier to work with as the program gets bigger
• It also makes it easier for anyone else that looks at the code, to work out what the program is doing
• It makes it easier to debug
• Several programmers can work on it at the same time
• Easier to update the code

Data types

• Integer - VB can store -2 147 483 648 to + 2 147 483 647
• Real/float
• Text/string
• Boolean
• Character
• Date/Time
• Pointer/reference
• This data type is used to store a value that will point to or reference a location in the memory of the computer
• If you think of memory as a series of pigeon-holes or addresses where instructions and data are stored, the pointer/reference is used in a program to go to a specific address
• Array
• Each individual name in the array is called an element
• Records
• Used to store a collection of related data items, where the items all have different data types

Built-in and user-defined data types

• User-defined data types are combining existing data types together