[ Non-logical Variables, Arrays, Bags, Shelves and Stores | The ECLiPSe Built-In Predicates | Reference Manual | Alphabetic Index ]

bag_count(+BagHandle, ?Count)

Get the number of entries in a bag

BagHandle: A bag
Count: A variable or integer

Description

This returns an integer corresponding to the number of entries currently in the bag. A fresh or erased bag has zero entries.

Fail Conditions

None

Resatisfiable

No

Exceptions

(4) instantiation fault: BagHandle is not instantiated
(5) type error: BagHandle is not a bag
(5) type error: List is instantiated but not to an integer
(40) stale object handle: BagHandle refers to an already destroyed bag

Examples

    ?- bag_create(B), bag_count(B, N0), bag_enter(B, one), bag_count(B, N1).
    N0 = 0
    B = 'BAG'(16'0030dc48)
    N1 = 1
    Yes (0.00s cpu)

See Also

bag_create / 1, bag_enter / 2, bag_count / 2, bag_erase / 1, bag_abolish / 1, bag_retrieve / 2, bag_dissolve / 2