array size

array size arrayName

Synopsis

array size arrayName

Description

Returns the number of variables in the array. If arrayName isn't the name of an array then 0 is returned.

Example:

% array set arr {foo 1 bar 2 grill 3}
% array size arr
3

It has been pointed out in the Tcl chatroom that array size is almost twice as slow as array statistics which returns much more data. If the speed matters, replace array size arrayName with [lindex [array statistics arrayName] 0]

DKF: However, please note that array statistics is not guaranteed to return the right answer. See this (trimmed) transcript for why:

% array set foo {a a b b c c d d e e}
% array stat foo
5 entries in table, 4 buckets
[...]
average search distance for entry: 1.2
% # Demonstrate the case that everyone thinks of first...
% unset foo(b)
% array stat foo
4 entries in table, 4 buckets
[...]
average search distance for entry: 1.3
% set foo(b) b
b
% array stat foo
5 entries in table, 4 buckets
[...]
average search distance for entry: 1.2
% # Now demonstrate the nasty case which makes things fall apart...
% upvar 0 foo(b) b
% unset b
% array stat foo
5 entries in table, 4 buckets
[...]
average search distance for entry: 1.2
% array size foo
4

MGS 2003-09-24: With 8.4.4, I find array size arrayName to be the quickest, with llength [array names arrayName] about two to three times as slow, and lindex [array statistics arrayName] 0 about ten times as slow.