= UBOUND( array [, dimension])

The UBOUND command (short for “upper bound”) is used to determine the highest index of an array. In other words, it tells you how far up the array goes.

Imagine you have a box of numbered chocolates. UBOUND tells you what the number of the last chocolate is. This is useful when you need to iterate over all the elements of an array, because it gives you the end point of the loop.

UBOUND and LBOUND are often used together to define the bounds of a FOR loop, and are complementary commands: they allow you to obtain complete information about the structure of an array. Knowing these two values, you can iterate over all the elements of the array, calculate its total size, and perform many other operations.

  DIM a(10,20)
  PRINT UBOUND(a,1) : REM it will print 20

 Ub

If you have encountered a problem using this command, if you think there is a bug or the explanation is unclear, please open an issue for this keyword on GitHub. Thank you!