Q58023: Multidimensional Limit for Undeclared (Non-DIMmed) Arrays

Article: Q58023
Product(s): See article
Version(s): 1.00 1.01 1.02 2.00 2.01 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom docerr SR# S900108-52 | mspl13_basic
Last Modified: 5-MAR-1990

When you reference an array without first dimensioning it with the DIM
statement, it is an undeclared array, and the highest element
subscript in each dimension always defaults to 10.

No errors should occur for an undeclared array that has 3 or fewer
dimensions, as in the following example:

   X(1,1,1)=0

However, if the undeclared (non-DIMMed) array has more than three or
four dimensions, such as X(1,1,1,1,1), you may get one or more of the
following error messages, depending upon the product version and the
number of dimensions referenced:

   Subscript out of range
   Out of data space
   Out of memory
   Array not dimensioned
   Array too big

Which error message displays depends on whether the array type is
string or numeric, how many dimensions you give the undeclared array,
whether the program is run in the QuickBASIC QB.EXE environment or
compiled with BC.EXE, and which version of BASIC or QuickBASIC is
used.

This information applies to Microsoft QuickBASIC Versions 1.00, 1.01,
1.02, 2.00, 2.01, 3.00, 4.00, 4.00b, and 4.50 for MS-DOS, to Microsoft
BASIC Compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2, and to
Microsoft BASIC Professional Development System (PDS) Version 7.00 for
MS-DOS and MS OS/2.

You can easily test to see exactly which errors are generated for all
combinations of the criteria above. Note that it is always safe to
access any undeclared array as long as it does not have more than 3
dimensions. (Note: Don't confuse dimensions with number of subscripts
per dimension.)

Regarding this topic, there is a difference between versions of
QuickBASIC up to 3.00 and Versions 4.00 and later. In Versions 4.00
and later, undeclared numeric arrays can have 4 or fewer dimensions,
and undeclared variable-length-string arrays can have 3 or fewer
dimensions. Versions of QuickBASIC earlier than 4.00 require all
undeclared arrays to have 3 or fewer dimensions. The restrictions that
apply to Versions 4.00 and later also apply to Microsoft BASIC
Compiler Versions 6.00 and 6.00b and Microsoft BASIC Professional
Development System (PDS) Version 7.00.

The following code examples illustrate the minimum number of
dimensions in the undeclared array that are needed to generate an
error for specific versions of QuickBASIC, BASIC Compiler, and BASIC
PDS:

'QuickBASIC Versions 1.00, 1.01, 2.00, 2.01, and 3.00:
PRINT a(1,2,3,4)  ' Numeric array, error for 4 or more dimensions
PRINT a$(1,2,3,4) ' Variable-length string array, error 4 or more dims

'QuickBASIC Versions 4.00, 4.00b, 4.50, BASIC compiler Versions 6.00
' and 6.00b, and BASIC PDS Version 7.00:
PRINT a(1,2,3,4,5) ' Numeric array, error for 5 or more dimensions
PRINT a$(1,2,3,4) ' Variable-length string array, for 4 or more dims.

To eliminate the errors, dimension the arrays to the size(s) you want
using the DIM statement.

The above limitations need to be added on the page referenced in the
Index entry under "Arrays, dimensioning" in the following manuals:

1. "Microsoft QuickBASIC 4.5: BASIC Language Reference" for Version
   4.50

2. "Microsoft QuickBASIC 4.0: BASIC Language Reference" manual for
   Versions 4.00 and 4.00b

3. "Microsoft QuickBASIC Compiler" Versions 2.0x and 3.00 manual

4. "Microsoft BASIC Version 7.0: Language Reference" manual

5. "Microsoft BASIC Compiler 6.0: BASIC Language Reference" for
   Versions 6.00 and 6.00b

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