COMFILE Technology's Documentation Library

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====== Variables ======

There are 5 types of variables in Cubloc BASIC.

  * Byte : 8 bit positive number, 0 to 255
  * Integer : 16 bit positive number, 0 to 65535
  * Long : 32 bit positive/negative number (-2147483648 to +2147483647)
  * Single : 32 bit floating point number (-3.402823E+38 to 3.402823E+38)
  * String : character string, 0 TO 127 bytes

{{ :cubloc:variables:byte_word_long.png?nolink |}}

*For storing negative numbers, please use LONG or SINGLE.
Use the Dim statement for declaring variables as shown below:

<code xbasic>
Dim A As Byte                  ' Declare A as Byte.
Dim B As Integer, C As Byte    ' Commas may NOT be used.
Dim ST1 As String * 12         ' Declare a String of 12 bytes.
Dim ST2 As String              ' String is 64 bytes default.
Dim AR(10) As Byte             ' Declare AR as a Byte Array.
Dim AK(10,20) As Integer       ' Declare AK as a 2-Dimensional Array
</code>

===== String =====

A String can be a maximum of 127 bytes in size. When the size is not
declared, a default size of 64 bytes will be assumed.

<code xbasic>
Dim ST As String * 14          ' For maximum usage of 14 bytes
Dim ST2 As String              ' Set as 64 byte String variable
</code>

When declaring a String as 14 bytes, an additional byte is allocated by the
processor to store a NULL terminating character. When storing "COMFILE
TECHNOLOGY" in a 14 byte String, the last 4 characters (bytes) will be truncated.

<code xbasic>
Dim ST As String * 14
ST = "COMFILE TECHNOLOGY"       ' "LOGY" is not stored
</code>

{{ :cubloc:variables:string_truncated.png?nolink |}}

In Cubloc BASIC, only the double-quote character(") can be used for
String constants and Strings; a single-quote characters (') can not be used.

<code xbasic>
ST = "COMFILE " TECHNOLOGY"           ' (") cannot be used inside the String.
ST = "COMFILE ' TECHNOLOGY"           ' (') cannot be used inside the String.
ST = "COMFILE , TECHNOLOGY"           ' (,) cannot be used inside the String.
</code>

Furthermore, Cubloc BASIC does not support character escape sequences.
Use CHR(&H22) to include a double-quote character(") in a String. Commas
and single-quotes also cannot be directly declared in a String. Use
CHR(&H27) to included a single-quote character (') and CHR(&H2C) to
included a comma (,).

Example for printing to an LCD:

<code xbasic>
Print Chr(&H22), "COMFILE TECHNOLOGY",Chr(&H22)           ' (")
Print Chr(&H27), "COMFILE " TECHNOLOGY",Chr(&H27)         ' (') Apostrophe
</code>

{{ :cubloc:variables:string_demo.png?nolink |}}

===== Concatenate Multiple Strings =====

To concatenate multiple strings together, use the + operator as shown below:

<code xbasic>
Dim a1 As String * 30
Dim a2 As String * 30
a1 = "Comfile "
a2 = "Technology "
a1 = a1 + a2 + ",Inc"
Debug a1,cr
</code>

The above program will show "Comfile Technology, Inc" on the debug screen.

{{ :cubloc:variables:string_demo2.png?nolink |}}

===== How to Access Individual Characters within a String =====

You can treat strings as a Byte array. Simply append "_A" after the name
of your string variable as shown below:

<code xbasic>
Dim ST1 As String * 12        ' ST1_A Array is created at the same time.
ST1 = "123"
ST1_A(0) = ASC("A")           ' Store A in the first character of ST1.
</code>

When you declare **Dim St1 as String * 12**, St1_A(12) is also declared
automatically by the Real-Time Operating System (RTOS). The string and
the array use the same memory space. Whether you use the string or the
array, you are still accessing same memory location.

The example below shows how to convert blank characters to z.

{{ :cubloc:variables:string_demo3.png?nolink |}}

====== About Variable Memory Space ======

In the CB220 and CB280, 2KB (2048 bytes) of data memory is available.
However, the memory is not dedicated entirely to variables. Some data
memory is reserved for use by peripherals like the DISPLAY and the RS232
buffers. An additional 80 bytes are used for the Debug statement.

Subroutines, functions, and interrupt routines, when executing, also
consume data memory, especially if they declare local variables. Of the
available 2048 bytes, about 1800 bytes can be used for global variables.
Space must be reserved for subroutines which may reduce the memory
available for global variables. However, this can often save memory, as the
local variables will be destroyed after the subroutine completes, releasing
the memory to be used again.

When the user creates buffers with SET DISPLAY or OPENCOM, data memory
will be consumed to allocate buffers.

===== Initializing Memory =====

In Cubloc BASIC, data memory is not cleared when powered on. The user
should initialize variables or use the RamClear statement to initialize all data
memory to 0. If data memory is not cleared, the values in memory could
potentially be anything. If the contents of memory are to be predictable,
you must either initialize each variable, or use the Ramclear statement.

In the case of battery backed-up modules, the variables will remember their
values after a power cycle (powering off and on). 



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