For a static array, each element of the array is reset. For a numeric array, each element is set to zero. For a string array, each element is set to the null string (and any space associated with the old string is deallocated).
For a dynamic array, the array becomes "un-dimensioned" (and all space associated with the array is deallocated). The elements of a dynamic array may be used only when the array is dimensioned. For the elements of an erased dynamic array to be useful, the array must be redimensioned.
Before an array appears in an erase statement, the array must appear in a statement which dimensions the array. An array may be erased more than once. An array which is a formal parameter to a subprogram may not be erased.
rem $static dim a(100) rem $dynamic dim b(100, 100) . . . erase a, bdemonstrates the use of erase for static and dynamic arrays. If the static array "a" is sparse, erasing it might be a convenient first step in its reuse. If the dynamic array "b" is large, erasing it might make needed memory space available.
from The Basmark QuickBASIC Programmerís Manual by Lawrence Leinweber