LlGetListEntryType

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Summary

Function: integer llGetListEntryType( list src, integer index );

Returns the type (an integer) of the entry at index in src.

• list src List containing the element of interest.
• integer index Index of the element of interest.

index supports negative indexes.
If index describes a location not in src then TYPE_INVALID is returned.

Specification

Index Positive Negative
First 0 -length
Last length - 1 -1

Indexes

  • Positive indexes count from the beginning, the first item being indexed as 0, the last as (length - 1).
  • Negative indexes count from the far end, the first item being indexed as -length, the last as -1.

Type Description
TYPE_INTEGER 1 integer
TYPE_FLOAT 2 float
TYPE_STRING 3 string
TYPE_KEY 4 key
TYPE_VECTOR 5 vector
TYPE_ROTATION 6 rotation
TYPE_INVALID 0 none

Caveats

  • If index is out of bounds the script continues to execute without an error message.
  • If a vector is stored in a list as "<7,5,0>" (as a string type, as opposed to <7,5,0> which is a vector type), its type will be returned as TYPE_STRING, not TYPE_VECTOR. The same applies for "1" being returned as a string instead of an integer, etc. There is no easy way to guess what the type should be from a string value. The users intent may not be obvious
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Examples

string get_list_entry_type_info(integer inputInteger)
{
    if (inputInteger == TYPE_INTEGER)
        return "integer";
 
    else if (inputInteger == TYPE_FLOAT)
        return "float";
 
    else if (inputInteger == TYPE_STRING)
        return "string";
 
    else if (inputInteger == TYPE_KEY)
        return "key";
 
    else if (inputInteger == TYPE_VECTOR)
        return "vector";
 
    else if (inputInteger == TYPE_ROTATION)
        return "rotation";
 
//  else
        return "<!-- invalid type --!>";
}
 
default
{
    touch_start(integer num_detected)
    {
        list listOfStuff = [
            <1.0, 2.0, 3.0, 4.0>,
            <1.0, 2.0, 3.0>,
            llGetKey(),
            "some random text",
            382.4,
            1];
 
        integer index = ~llGetListLength(listOfStuff);
 
        // start with -length and end with -1
        while (++index)
        {
            integer type = llGetListEntryType(listOfStuff, index);
            string entry2string = llList2String(listOfStuff, index);
 
            llSay(0, "'" + entry2string + "' has the list-entry-type: '" + get_list_entry_type_info(type) + "'");
        }
    }
}

Useful Snippets

This function has two primary uses: serializing a list to a string, debugging.

//A simple list serializer and deserializer.
//This will round floats to 6 decimal places and not handle strings with embedded "|" characters
 
string serialize(list input){
    integer len = ~llGetListLength(input);
    string build = (string)(~len);
    while(++len)
    {
        build += "|" + (string) llGetListEntryType(input, len) + 
             "=" + llList2String(input, len);        //not safe if list item could contain "|" character
    }
    return build;
}
 
list deserialize(string input){
    integer len = ~(integer)input;//the length is everything before the "|", which is where (integer) stops
    list build = [];
    list pair = llParseString2List(input, ["|"], []);
    string value;
    list replace;
    while(++len)
    {
        integer type = (integer)(value = llList2String(pair, len));
        value = llDeleteSubString(value, 0, llSubStringIndex(value, "="));
        if (type == TYPE_INTEGER)
            replace = [(integer)value];
        else if (type == TYPE_FLOAT)
            replace = [(float)value];
        else if (type == TYPE_STRING )
            replace = [value];
        else if (type == TYPE_KEY)
            replace = [(key)value];
        else if (type == TYPE_VECTOR)
            replace = [(vector)value];
        else if (type == TYPE_ROTATION)
            replace = [(rotation)value];
        pair = llListReplaceList(pair, replace, len, len);
    }
    return pair;
}

This snippet produces an LSL formatted dump of a list that can be pasted back into LSL.

//A list dumper that produces an output suitable for pasting back into LSL as a variable initialization.
string list_dump(list mylist)
{
    string output = "[";
    integer i;
    integer count = (mylist != [] );   // length of list (shorthand)
    integer type;
    for ( ; i < count; ++i) 
    {
        if (i) 
            output += ","; 
        type = llGetListEntryType(mylist, i); 
        if (type == TYPE_KEY)
            output += "(key)";
        if (type == TYPE_STRING || type == TYPE_KEY)  
            output += "\""; 
        output += llList2String(mylist, i); 
        if (type == TYPE_STRING || type == TYPE_KEY)
            output += "\""; 
    }
    return (output + "]");
}

For a more complex and robust list (de)serializer see TightListType.

See Also

Functions

•  llList2Float
•  llList2Integer
•  llList2Key
•  llList2Rot
•  llList2String
•  llList2Vector

Articles

•  Negative Index

Deep Notes

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