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Appendix C: Rapid-Q Supported Data Types
Rapid-Q Documentation by William Yu (c)1999 Appendix C: Data Types


Introduction to Data Types

A data type is just a definition. It is used to bind a variable to its definition and cannot be changed once bound (except for VARIANT type variables). For example, if a variable is bound to a STRING data type, it cannot change itself to an INTEGER definition. A variable can be assigned any one of these supported data types, BYTE, WORD, DWORD, SHORT, LONG/INTEGER, SINGLE, DOUBLE, STRING, VARIANT, and fixed-length strings. There are also such things as User Defined Data Types, which will be discussed in another section. Some BASIC implementations hold INTEGER as a 16-bit value, while Rapid-Q chooses to go 32-bit. So if you're worried about converting your old code, make sure to replace all occurrences of INTEGER with SHORT.

How to use data types
Since Rapid-Q is a BASIC language, there are 2 ways to define your variables. You can choose to do it explicitly using DIM
    DIM myNum AS LONG
    DIM myStr AS STRING
Similarly, you can attach a suffix symbol which describes the variable type:
    myNum& = 234
    myStr$ = "abc"
Chapter 3 has a list of these suffixes, but are listed here again for your convenience:
    Type       ID  Size  Range
    --------- ---- ---- -------------
    Byte        ?   1   0..255
    Word       ??   2   0..65535
    Dword     ???   4   Only Linux version for now...
    Short       %   2   -32768..32767
    Integer     &   4   -2147483648..2147483647
    Long        &   4   -2147483648..2147483647
    Single      !   4   1.5 x 1045..3.4 x 1038
    Double      #   8   5.0 x 10324..1.7 x 10308
    String      $
A variant data type has no suffix, so you'll have to use DIM instead, or change the default DIM operation.
    $OPTION DIM VARIANT

    myVar = "hello!"
myVar is defined as a VARIANT since we've changed the default data type for DIM. Whenever Rapid-Q comes across an undefined symbol (with no suffix), it will choose the data type according to traditional BASIC. Traditionally, this has been choosen to be either SINGLE or DOUBLE. With Rapid-Q, you can choose any of the existing data types as the default one.

Variant data type
A Variant is a special kind of data type, since a Variant can mutate. Don't be afraid, it won't mutate to a virus or anything like that. It simply changes types on the fly, as needed. Even a simple operation like addition changes when you add 2 variants together. Take this for example:
   DIM V1 AS VARIANT, V2 AS VARIANT

   V1 = 101
   V2 = "99.5"

   PRINT V1+V2  '-- Output is 200.5
As you'll notice V2 is originally assigned a string, but V2 has changed its type to a floating point number when the addition takes place. Note that V2 is still a string, it just mutated itself for that one operation. Similarly,
   DIM V1 AS VARIANT, V2 AS VARIANT

   V1 = "101"
   V2 = 99.5

   PRINT V1+V2  '-- Output is 10199.5
In this case, V2 was originally a floating point number, but changed its type during the addition operation to a string. Notice how the order of operation defines the mutation. In the previous example, V1 was a number, so V1+V2 results in a numeric expression, while the above example produces a string.


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