Designing Games with Game Maker - YoYo Games

Maps
given id.
ds_list_size(id) Returns the number of values stored in the list.
ds_list_empty(id) Returns whether the list is empty. This is the same as
testing whether the size is 0.
ds_list_add(id,val) Adds the value at the end of the list.
ds_list_insert(id,pos,val) Inserts the value at position pos in the list.
The first position is 0, the last position is the size of the list minus 1.
ds_list_replace(id,pos,val) Replaces the value at position pos in the
list with the new value.
ds_list_delete(id,pos) Deletes the value at position pos in the list.
(Position 0 is the first element.)
ds_list_find_index(id,val) Find the position storing the indicated
value. If the value is not in the list -1 is returned.
ds_list_find_value(id,pos) Returns the value stored at the indicated
position in the list.
ds_list_sort(id,ascend) Sorts the values in the list. When ascend is true
the values are sorted in ascending order, otherwise in descending order.
ds_list_shuffle(id) Shuffles the values in the list such that they end up
in a random order.
ds_list_write(id) Turns the data structure into a string and returns this
string. The string can then be used to e.g. save it to a file. This provides an
easy mechanism for saving data structures.
ds_list_read(id,str) Reads the data structure from the given string (as
created by the previous call).
In quite a few situations you need to store pairs consisting of a key and a value. For example,
a character can have a number of different items and for each item it has a particular number
of those. In this case the item is the key and the number is the value. Maps maintain such
pairs, sorted by key. You can add pairs to the map and search for the value corresponding to
certain keys. Because the keys are sorted you can also find previous and next keys.
Sometimes it is also useful to use a map to just store keys without a corresponding value. In
that case you can simply use a value of 0. The following functions exist: