# 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).