Variable
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Contents |
General Concepts
- Variable
- A data value that is editable when the program executes.
- Variables have 3 properties:
- Memory location to store variable,
- type of data stored in memory location,
- and name used to refer to memory location.
Programming Languages
Java
- Variable Declaration Syntax
- <data type> <variable> ;
- <data type>
- Any of Java's primitive data types.
- <variable>
- a valid identifier, or a series of valid identifiers separated by commas. E.g. variable1, variable2, variable3 ;
- Variables can be declared and initialised at the same time:
- E.g. int variable1 = 10 ;
- Naming Conventions
- Names can only contain letters, digits, underscores, or dollar signs.
- Names are case sensitive.
- First letter must be a lower case character.
- Where names/identifiers have multiple words, the first letter of all words after the first will be upper case (don't use underscores for spaces).
- array variables use the plural names.
VBA
- Variable Declaration Syntax
- Dim <variable> As <data type>
- <variable>
- a variable name following the naming conventions for VBA variables.
- <data type>
- one of VBAs primitive data types.
- Naming Conventions
- must begin with a letter (a-z or A-Z) or an underscore
- cannot contain a period (.) or a special character
- must not contain a space
- must not exceed 255 characters. You should limit the name of a variable to 30 characters
- must be unique in the same scope
- name must be preceded by 3 letter prefix according to type
| Data Type | Prefix |
|---|---|
| Boolean | bln |
| Byte | byt |
| Date/Time | dtm |
| Double | dbl |
| Error | err |
| Integer | int |
| Long | lng |
| Object | obj |
| Single | sng |
| String | str |
| Currency | cur |
| Variant | var |
Option Explicit
- Variables don't need to be declared before use, unless Option Explicit is specified at the top of the source code.
