OPTION BASE - mkilgore/QB64pe GitHub Wiki

The OPTION BASE statement is used to set the default lower bound of arrays.

OPTION BASE {0|1}

• This statement affects array declarations where the lower bound of a dimension is not specified.
• When used, OPTION BASE must come before any array declarations (DIM) to be affected.
• By default, the lower bound for arrays is zero, and may be changed to one using the statement.
• Otherwise, arrays will be dimensioned from element 0 if you DIM just the upper bounds.
• You can also set other array boundaries by using TO in the DIM declaration such as DIM array(5 TO 10)

Example 1: Set the default lower bound for array declarations to one.

OPTION BASE 1

' Declare a 5-element one-dimensional array with element indexes of one through five.
DIM array(5) AS INTEGER

PRINT LBOUND(array)

 1

Example 2: Set the default lower bound for array declarations to zero.

' Declare an 18-element two-dimensional array with element indexes of zero through two 
' for the first dimension, and 10 through 15 for the second dimension.
DIM array(2, 10 to 15) AS INTEGER

PRINT LBOUND(array, 1)
PRINT LBOUND(array, 2)

 0
 10

• Arrays, LBOUND, UBOUND
• DIM, REDIM, STATIC, COMMON