Category:LSL List

A list is a special kind of data type which can contain zero or more elements.

Lists are signified by square brackets surrounding their elements; the elements inside are separated by commas.

Examples:

[0,1,2,3,4]
["Yes","No","Perhaps"]

(Note: to be clear for those who have other programming backgrounds, there are no arrays in LSL: only lists.)

Diverse Data Types

Not all elements in a list need to be the same type of element. In the same list, you can store strings, integers, floats, vectors, etc, right side by side.

Example: //a list with an integer, a float, a string, and a vector.

[1,14.154,"Isn't this fun?",<0,0,0>]

However, a list may not contain another list (i.e. you can't nest them.)

[1, "one", 2, "two"] + [3, "three"] returns [1, "one", 2, "two", 3, "three"]
not [1, "one", 2, "two", [3, "three"]]

When you add an element to a list, the list remembers automatically what data type the value was.

Generally, because you're the one adding something to a list, you know what datatype is in what place in the list, and you retrieve it out of the list with the appropriate llList2<type> function such as: llList2String, llList2Vector, etc. (more on this later.)

If for some reason, though, you need to test what data type an element is in a list, you can use the llGetListEntryType function.

Tip! When adding a float to a list, always add it with a decimal point (e.g 1.0 as opposed to 1) to ensure that it is preserved as a float.

Counting place in a list vs list length

It's important at the outset to note the following (which can trip up even experienced minds when they are battle-weary):

["Yes","No","Perhaps"]

The length of this list is 3, because it has 3 elements in it.

BUT, counting to determine an element's place in its list (aka "indexing") starts at 0 -- NOT 1.

The position of "Yes" in the above list is 0, "No" is at position 1, and "Perhaps" is at position 2.

Consequently, if you have 7 elements in a list, the last item in the list will be at position 6.

List Limits

While a script is running, a list can grow dynamically as large as needed, limited only by the amount of memory that is available in the script.

However, at compile (aka save) time, there is a 72 element limit to pre-defined lists hardcoded in the script. Such long, predefined lists are common, for example, when someone is offering the user a plethora of colour choices.

Tip! If you really need 72 or more such choices in a pre-defined list, just make 2 (or more) lists that don't upset the compiler, and join them together in state_entry() or wherever appropriate:

biggerlist = biglist01 + biglist02;

Joining Lists (aka Concatenation)

Lists can be joined simply by using the + sign:

newlist = list01 + list02;

newlist = list01 + ["red","brown",<0,0,0>];

Extended List Operations

These functions have been created and contributed by LSL users to perform operations not covered by built-in LSL functions.