The Length Operator

The length operator is denoted by the unary operator #. The length of a string is its number of bytes (that is, the usual meaning of string length when each character is one byte).

The length of a table t is defined to be any integer index n such that t[n] is not null and t[n+1] is null; moreover, if t[1] is null, n can be zero. For a regular array, with non-null values from 1 to a given n, its length is exactly that n, the index of its last value. If the array has "holes" (that is, null values between other non-null values), then #t can be any of the indices that directly precedes a null value (that is, it may consider any such null value as the end of the array).