STACK

$X\ --\ I$

DESCRIPTION

Returns the number of elements in the value of its operand if the operand is an array, stack or a string.
If the operand is a dictionary, length returns the current number of entries it contains.
If the operand is a name object, the length returned is the number of characters in the text string that defines it.
In all other cases length returns 1.

ORIGIN

Core code registered in systemdict.