Difference between revisions of "LlListFindList"

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(-1 returned from llListFindList is not a generic error (of which nothing is known). It has a specific meaning of NOT FOUND)
(Clarify background for using ~)
Line 54: Line 54:
<lsl>if(~llListFindList(myList, (list)item))
<lsl>if(~llListFindList(myList, (list)item))
{//it exists
{//it exists
     //This works because ~(-1) == 0
     // This works because ~(-1) produces 0, but ~ of any other value produces non-zero and causes the 'if' to succeed
     //It saves bytecode and is faster then doing != -1
    // So any return value (including 0) that corresponds to a found item, will make the condition succeed
     //This is a bitwise NOT (~) not a negation (-)
     // It saves bytecode and is faster then doing != -1
     // This is a bitwise NOT (~) not a negation (-)
}</lsl>
}</lsl>
|also_functions=
|also_functions=

Revision as of 12:57, 13 January 2014

Summary

Function: integer llListFindList( list src, list test );
0.0 Forced Delay
10.0 Energy

Returns the integer index of the first instance of test in src.

• list src what to search in (haystack)
• list test what to search for (needle)

If test is not found in src, -1 is returned.
The index of the first entry in the list is 0
If test is found at the last index in src the positive index is returned (5th entry of 5 returns 4).

Caveats

  • Strict type matching and case sensitivity is enforced.
    • "1" != 1
    • "1.0" != 1.0
    • 1 != 1.0
    • "a822ff2b-ff02-461d-b45d-dcd10a2de0c2" != (key)"a822ff2b-ff02-461d-b45d-dcd10a2de0c2"
    • "Justice" != "justice"
  • If test is an empty list the value returned is 0 rather than -1.

Examples

<lsl>list numbers = [1, 2, 3, 4, 5]; default {

   state_entry()
   {
       integer index = llListFindList(numbers, [3]);
       if (index != -1)
       {
           list three_four = llList2List(numbers, index, index + 1);
           llOwnerSay(llDumpList2String(three_four, ","));
           // Object: 3,4
       }
   }

}</lsl> <lsl>//You can also search for two items at once to find a pattern in a list list avatarsWhoFoundMagicLeaves = ["Fire Centaur","Red Leaf"]; default {

   state_entry()
   {
       integer index = llListFindList(avatarsWhoFoundMagicLeaves, ["Fire Centaur","Red Leaf"]);
       if (index != -1)
       {
           list output = llList2List(avatarsWhoFoundMagicLeaves, index, index + 1);
           llOwnerSay(llDumpList2String(output, ","));
           // Object: Fire Centaur, Red Leaf
       }
   }
}</lsl>

Useful Snippets

An easy way to see if an item exists in a list... <lsl>if(~llListFindList(myList, (list)item)) {//it exists

   // This works because ~(-1) produces 0, but ~ of any other value produces non-zero and causes the 'if' to succeed
   // So any return value (including 0) that corresponds to a found item, will make the condition succeed
   // It saves bytecode and is faster then doing != -1
   // This is a bitwise NOT (~) not a negation (-)

}</lsl>

See Also

Functions

•  llSubStringIndex Find a string in another string

Deep Notes

Signature

function integer llListFindList( list src, list test );