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Arrays and Conversion

DIM arrays are BBj's fixed-size, typed arrays -- they have been part of the language since the original Business BASIC. BBj provides the VECTOR() function to convert arrays into BBjVectors, bridging legacy array code with modern collection APIs.

DIM Arrays​

BBj arrays are declared with DIM and have a fixed size set at creation. String arrays use the $ suffix, numeric arrays do not:

rem String array (3 elements: index 0, 1, 2)
dim names$[2]

rem Numeric array (6 elements: index 0 through 5)
dim values[5]

Arrays are 0-based. The dimension number is the highest valid index, so dim a$[2] creates 3 elements (indexes 0, 1, 2).

Populating and Accessing​

Set values by index and read them with a for loop:

dim names$[2]
names$[0] = "Alice"
names$[1] = "Bob"
names$[2] = "Charlie"

for i = 0 to 2
    print names$[i]
next i

Accessing an index outside the declared range causes a runtime error. Unlike BBjVector, DIM arrays cannot grow after creation.

Converting Arrays to BBjVector​

The VECTOR() function converts a DIM array into a BBjVector. This is useful when you have array data that needs to be passed to methods expecting a BBjVector or java.util.List:

dim names$[2]
names$[0] = "Alice"
names$[1] = "Bob"
names$[2] = "Charlie"

rem Convert to BBjVector (BBj 16.0+)
vect! = vector(names$[])
print "Vector size: ", vect!.size()

for i = 0 to vect!.size() - 1
    print vect!.getItem(i)
next i

The VECTOR() function was added in BBj 16.0. The syntax is vector(array[]) -- note the empty brackets after the array name. The resulting BBjVector is a copy; changes to the vector do not affect the original array.

Comparison Table​

CollectionSizeTypesBest For
DIM arrayFixedSingle typeKnown-size data, performance-critical loops
BBjVectorDynamicMixedGeneral-purpose, BBjAPI integration
java.util.ArrayListDynamicMixedJava library interop
java.util.HashMapDynamicKey-valueLookup tables, configuration

DIM arrays are fastest for simple indexed access. BBjVector is the default for most BBj work. Use Java collections when working with Java libraries or when you need key-value storage.

A Note on String Templates​

BBj also supports string templates -- structured record definitions that overlay a string variable. They are used extensively in file I/O to define record layouts:

dim a$:tmpl$

String templates are covered in detail in the File I/O and Record Access chapter.

Reading Legacy Code

See Reading Legacy Code for DIM-as-collection, REDIM, parallel arrays, and other historical collection patterns.

Further Reading