lookup

Returns an iterator pointing to the position of the first item found equal to data according to cmp_func and cmp_data.

If more than one item is equal, it is not guaranteed that it is the first which is returned. In that case, you can use next and prev to get others.

cmp_func is called with two items of the this and user_data. It should return 0 if the items are equal, a negative value if the first item comes before the second, and a positive value if the second item comes before the first.

This function will fail if the data contained in the sequence is unsorted. Use insert_sorted or insert_sorted_iter to add data to your sequence or, if you want to add a large amount of data, call sort after doing unsorted insertions.

Parameters:

this	a Sequence
data	data to lookup
cmp_func	the function used to compare items in the sequence
cmp_data	user data passed to cmp_func

Returns:

an SequenceIter pointing to the position of the first item found equal to data according to cmp_func and cmp_data, or null if no such item exists