= LBOUND( array [, dimension])

The LBOUND command (short for “lower bound”) is used to determine the lowest index of an array. In other words, it tells you where the count of elements in an array begins.

Imagine an array as a cabinet with many numbered drawers. LBOUND tells you what the number of the first drawer is. This is useful when you need to iterate through all the elements of an array, because it gives you the starting point of the loop.

If you have an array with multiple dimensions, you can specify the dimension for which you want to find the lower bound:

LBOUND is essential when you write FOR loops to iterate through all the elements of an array. It allows you to set the initial value of the loop counter correctly.

  DIM a(10,20)
  PRINT LBOUND(a) : REM it will print 0

 Lb

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!