Programming Perl, 4th Edition

delete

delete EXPR

This function deletes an element (or a slice of elements) from the specified hash or array. (See unlink if you want to delete a file.) Deleted elements are normally returned in the order specified, although this behavior is not guaranteed for tied variables such as DBM files. After the delete operation, the exists function returns false on any deleted key or index. (In contrast, after the undef function, the exists function continues to return true, because the undef function only undefines the value of the element, but doesn’t delete the element itself.)

Deleting from the %ENV hash modifies the environment. Deleting from a hash tied to a (writable) DBM file deletes the entry from that DBM file.

Deleting from an array causes the element at the specified position to revert to a completely uninitialized state, but it doesn’t close up the gap, since that would change the positions of all subsequent entries. Use a splice for that. However, if you delete the final element in an array, the array size does shrink by one or more, depending on the position of the next largest existing element, if any.

Calling delete on array values is deprecated and likely to be removed in some future version of Perl.

EXPR can be arbitrarily complicated if the final operation is a hash or array lookup:

# set up array of array of hash $dungeon[$x][$y] = \%properties; # delete one property from hash delete $dungeon[$x][$y]{"OCCUPIED"}; # delete three properties all at once from hash delete @{ ...