NULL terminated array - why not everywhere?

[froggyswamp]

Folks, while learning C & Gtk I found that in some cases one is required to pass a NULL terminated string array. As far as I understand NULL is required for the other function to detect the length of the array.
If so, isn't it a small inconsistency that in other areas one is required to also pass the size (of whatever array) as a separate parameter? or is here performance at stake? Just wondering.

EDIT:
oops apparently the post before mine clarified this
http://ubuntuforums.org/showthread.php?t=1300667

[MadCow108]

in addition to the reason in the other thread (determining size needs a loop over whole array) terminated arrays have the disadvantage that the terminating construct can not appear in the data of the array.

e.g. a null terminated array cannot contain null bytes.
This is no problem with cstrings or certain arrays of pointers as no character contained in a string is coded to null and no legit pointer should have the value null.
But in general this is a problem.