Difference between revisions of "LlSubStringIndex"

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(useful snippets -- trust llGetSubString to understand negative indices, rather than adding llStringLength(haystack) on ourselves)
(restructure startswith to work like endswith, rather than burning run time to search all the haystack in the often common case of needle not found)
Line 49: Line 49:
integer startswith(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
integer startswith(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
{
return (0 == llSubStringIndex(haystack,needle));
return llGetSubString(haystack, 0, llStringLength(needle) - 1) == needle;
}
}
</pre>
</pre>

Revision as of 16:15, 16 October 2007

Summary

Function: integer llSubStringIndex( string source, string pattern );
0.0 Forced Delay
10.0 Energy

Returns an integer that is the index of pattern in source.

• string source
• string pattern

If pattern is not found in source, -1 is returned.
The index of the first character in the string is 0

Caveats

  • Performs a literal match (case sensitive).
    • Wildcards and RegEx are not supported.
  • Attempting to match an empty string ("") will return 0 instead of -1.

Examples

Matching against last names:

default
{
    state_entry()
    {
        llSensorRepeat("", NULL_KEY, AGENT, PI, 96.0, 20);
    }
    
    sensor(integer NumDet)
    {
        integer i;
        
        //Loop through all the sensor data and match against " Linden", 
        //this causes it to match with any last name of Linden (since there can't be spaces before the firstname)
        //Alternatively you could match a firstname with "FirstName "
        for(i = 0; i < NumDet; ++i)
            if(~llSubStringIndex(llDetectedName(i), " Linden"))
                llInstantMessage(llDetectedKey(i), "Hello, I see you!");
    }
}

Useful Snippets

Tests to see if one string contains a copy of another:

1. Clear and conventional:

integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
    return 0 <= llSubStringIndex(haystack, needle);
}
integer startswith(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
	return llGetSubString(haystack, 0, llStringLength(needle) - 1) == needle;
}
integer endswith(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
	return llGetSubString(haystack, -llStringLength(needle), -1) == needle;
}

Note: Some of the snippets above return a result without ever calling llSubStringIndex.

2. Clever and smaller (tests contains in ~54 bytes rather than ~60):

integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
    return ~llSubStringIndex(haystack, needle);
}

Note: The llSubStringIndex function returns -1 only when not found and the ~ operator returns zero only for -1, so the arcane combination ~llSubStringIndex returns zero only for not found, else nonzero for found.

Note: Smaller was not noticeably faster or slower when our Code Racer and Efficiency Tester harnesses measured the expression { contains("wiki.secondlife.com", "wiki"); }.

See Also

Functions

•  llListFindList Find a list in another list
•  llGetSubString Copy out part of a string of characters

Deep Notes

Signature

function integer llSubStringIndex( string source, string pattern );