Difference between revisions of "LlSubStringIndex"

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m (*Attempting to match an empty string ("") will return 0 instead of -1.)
(also present the drearily-conventional correct-at-a-glance snippet that means contains, not just the smaller snippet -- and note as yet we have no faster snippet)
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</pre>
</pre>
|helpers=
|helpers=
An easy way to see if a string exists in another string...
Easy ways to see if a string exists in another string...
 
1. Correct at a glance and drearily conventional:
<pre>
<pre>
if(~llSubStringIndex(myString, str))
integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{//it exists
{
    //This works because ~(-1) == 0 and any non-zero integer is considered true.
     return 0 <= llSubStringIndex(haystack, needle);
    //It saves bytecode and is faster then doing != -1
     //(It's also significantly less readable (unless you include the comments)
    // and most developers I know will advice against these kind of practices. -OddesE Oh)
}
}
</pre>
</pre>
2. Smaller (~54 bytes rather than ~60):
<pre>
integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
    return ~llSubStringIndex(haystack, needle);
}
</pre>
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 when our [[Efficiency Tester]] measured the expression <nowiki>{ contains("wiki.secondlife.com", "wiki"); }</nowiki>.
|also_functions=
|also_functions=
{{LSL DefineRow||[[llListFindList]]|Find a list in another list}}
{{LSL DefineRow||[[llListFindList]]|Find a list in another list}}

Revision as of 05:32, 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

Easy ways to see if a string exists in another string...

1. Correct at a glance and drearily conventional: 

integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
    return 0 <= llSubStringIndex(haystack, needle);
}

2. Smaller (~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 when our Efficiency Tester measured the expression { contains("wiki.secondlife.com", "wiki"); }.

See Also

Functions

•  llListFindList – Find a list in another list

Deep Notes

Signature

function integer llSubStringIndex( string source, string pattern );
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