Difference between revisions of "LlSubStringIndex"

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(confirm our Efficiency Tester claims of equal run time with the much different Code Racer benchmark)
m (collect all our clear and conventional examples to look for one string inside another all together)
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</pre>
</pre>
|helpers=
|helpers=
Easy ways to see if a string exists in another string...
Tests to see if one string contains a copy of another:
 
1. Clear and conventional:


1. Correct at a glance and drearily conventional:
<pre>
<pre>
integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
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</pre>
</pre>


2. Smaller (~54 bytes rather than ~60):
<pre>
<pre>
integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
integer startswith(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
{
    return ~llSubStringIndex(haystack, needle);
return (0 == llSubStringIndex(haystack,needle));
}
}
</pre>
</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 [[Code Racer]] and [[Efficiency Tester]] harnesses measured the expression <nowiki>{ contains("wiki.secondlife.com", "wiki"); }</nowiki>.


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


NOTE: This function doesn't use llSubStringIndex
Note: Some of the functions above calculate the answer without calling llSubStringIndex.
 
2. Smaller (tests contains in ~54 bytes rather than ~60):
 
<pre>
<pre>
integer endswith(string haystack, string needle)
integer contains(string haystack, string needle) // http://wiki.secondlife.com/wiki/llSubStringIndex
{
{
return (llGetSubString(haystack,llStringLength(haystack)-llStringLength(needle),-1) == needle);
    return ~llSubStringIndex(haystack, needle);
}
}
</pre>
</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 [[Code Racer]] and [[Efficiency Tester]] harnesses 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 17:04, 16 October 2007

Summary

Function: integer llSubStringIndex( string source, string pattern );

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.
All Issues ~ Search JIRA for related Bugs

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 (0 == llSubStringIndex(haystack,needle));
}

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

Note: Some of the functions above calculate the answer without calling llSubStringIndex.

2. 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 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

Deep Notes

Search JIRA for related Issues

Signature

function integer llSubStringIndex( string source, string pattern );
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