Arrays are created and manipulated with the array functions. An array must first be created with `create_array` or `temp_array`, specifying how many data elements the array can hold. You can store any of ints, floats and strings in an array, and can mix all 3 in a single array. The ID returned by `create_array` or `temp_array` can then be used with the other array functions. Arrays are shared between all scripts (i.e. you can call `create_array` from one script, and then use the returned ID from another script). They are also saved across savegames.
Arrays created with `temp_array` will be automatically freed at the end of the frame. These functions are safe, in that supplying a bad ID or trying to access out of range elements will not crash the script. `create_array` is the only function that returns a permanent array, all other functions which return arrays (`string_split`, `list_as_array`, etc,) all return temporary arrays. You can use `fix_array` to make a temporary array permanent.
Array elements are accessed by index or key. For example:
```js
// this code puts some string in array "list" at index 5:
list[5]:="Value";
```
There are 2 different types of arrays currently available:
* **Lists** - a set of values with specific size (number of elements), where all elements have numeric indexes starting from zero (0) up to array length minus one.
For example:
```js
// this creates list with 3 elements. Element "A" has index 0, element "B" has index 1, element "C" - 2
list := ["A", "B", "C"];
```
Limitations:
- all indexes are numeric, starting from 0;
- to assign value to a specific index, you must first resize array to contain this index
(for example, if list is of size 3 (indexes from 0 to 2), you can't assign value to index 4 unless you change list size to 5 first).
* **Maps** (or associative arrays) - a set of key=>value pairs, where all elements (values) are accessed by corresponding keys.
Differences from list:
- maps don't have specific size (to assign values, you don't need to resize array first);
- keys, just like values, can be of any type (but avoid using -1 as array keys or you won't be able to use some functions reliably).
Both array types have their pros and cons and are suited for different tasks.
___
### ARRAYS SYNTAX
Basically arrays are implemented using number of new operators (scripting functions). But for ease of use, there are some new syntax elements:
* Accessing elements. Use square brackets:
```js
display_msg(arr[5]);
mymap["price"] := 515.23;
```
* Alternative accessing for maps. Use dot:
```js
display_msg(mymap.name);
mymap.price := 232.23;
```
* Array expressions. Create and fill arrays with just one expression:
```js
// create list with 5 values
[5, 777, 0, 3.14, "Cool Value"]
// create map:
{5: "Five", "health": 50, "speed": 0.252}
```
__NOTES:__
Make sure to call `fix_array` if you want new array to be available in the next frame or `save_array` if you want to use it for a longer period (see next section for details).
* Iterating in loop. Use `foreach` key word like this:
```js
foreach (item in myarray) begin
// this block is executed for each array element, where "item" contains current value on each step
end
// alternative syntax:
foreach (key: item in myarray) begin
// "key" will contain current key (or numeric index, for lists)
end
```
See **sslc_readme.txt** file for full information on new SSL syntax features.
___
### STORING ARRAYS
Apart from lists/maps, arrays are divided by how they are stored.
There a 3 types of arrays:
* **Temporary**. They are created using `temp_array` function or when using array expressions.
Arrays of this type are auto-deleted at the end of the frame. So, for example, if you have a global script which runs at regular intervals, where you create a temporary array, it will not be available next time your global script is executed.
* **Permanent**. They are created using `create_array` function or `fix_array` (from pre-existing temporary array).
This type of arrays are always available (by their ID) until you start a new game or load a saved game (at which point they are deleted).
* **Saved**. If you want your array to really stay for a while, use function `save_array` to make any array "saved". However, they are, like permanent arrays, "deleted" from memory when loading game. In order to use them properly, you must load them from the savegame using `load_array` whenever you want to use them.
Example:
```js
variable savedArray;
procedure start begin
if game_loaded then begin
savedArray := load_array("traps");
end else begin
foreach trap in traps begin
....
end
end
end
```
___
### PRACTICAL EXAMPLES
**Use arrays to implement variable-argument procedures:**
```js
// define it
procedure give_item(variable critter, variable pidList) begin
**Create arrays of objects (maps) for advanced scripting:**
```js
variable traps;
procedure init_traps begin
// just a quick example, there is a better way of doing it...
traps := load_array("traps");
if (traps == 0) then begin
traps := [];
save_array("traps", traps);
end
foreach k: v in traps begin
traps[k] := load_array("trap_"+k); // each object is stored separately
end
end
procedure add_trap(variable trapArray) begin
variable index;
index := len_array(traps);
save_array("trap_"+k, trapArray);
array_push(traps, trapArray);
end
// use them:
foreach trap in traps begin
if (self_elevation == trap["elev"] and tile_distance(self_tile, trap["tile"]) < trap["radius"]) then
// kaboom!!!
end
end
```
___
### ARRAY OPERATORS REFERENCE
_*mixed means any type_
#### `int create_array(int size, int flags)`
- creates permanent array (but not "saved")
- if `size >= 0`, creates list with given size
- if `size == -1`, creates map (associative array)
- if `size == -1` and `flags == 2`, creates a "lookup" map (associative array) in which the values of existing keys are read-only and can't be updated. This type of array allows you to store a zero (0) key value
* NOTE: in earlier versions (up to 4.1.3/3.8.13) the second argument is not used, just use 0
- returns array ID (valid until array is deleted)
#### `int temp_array(int size, int flags)`
- works exactly like `create_array`, only created array becomes "temporary"
#### `void fix_array(int arrayID)`
- changes "temporary" array into "permanent" ("permanent" arrays are not automatically saved into savegames)
- there are number of special negative values of "size" which perform various operations on the array, use macros `sort_array`, `sort_array_reverse`, `reverse_array`, `shuffle_array` from **sfall.h** header
* There is an INI parameter **arraysBehavior** in **Misc** section of ddraw.ini. If set to 0, all scripts which used sfall arrays before should work. This basically changes that `create_array` will create permanent arrays which are "saved" by default and their ID is also permanent. It is 1 by default.
Saved arrays are stored in **sfallgv.sav** file (in savegame) in new (more flexible) format, just after the old arrays. So basically, when you load older savegame, sfall will load arrays from old format and save them to new format on next game save. If you load savegame made with sfall 3.4 using sfall 3.3 (for example), game shouldn't crash, but all arrays will be lost.
* Previously you had to specify size in bytes for array elements. This parameter is now ignored and you can store strings of arbitrary length in arrays.
