data to lookup
the function used to compare items in the sequence
user data passed to @cmp_func
an #GSequenceIter 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
2.28
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 g_sequence_iter_next() and g_sequence_iter_prev() to get others.
@cmp_func is called with two items of the @seq 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.