Difference between revisions of "LlStringTrim"

From Second Life Wiki
Jump to navigation Jump to search
(llReplaceSubString should be promoted as the preferred approach instead of old hacks)
(a much faster (~2x) and memory efficient (didn't measure exactly, but several kB on a 1 kB string) approach for removing doubled spaces; regrouped obsolete examples as "maybe don't use these")
 
Line 80: Line 80:
** Other whitespace characters defined in Unicode, such as non-breaking space (0xa0) or specific-width spaces in the 0x2000 range are not stripped.
** Other whitespace characters defined in Unicode, such as non-breaking space (0xa0) or specific-width spaces in the 0x2000 range are not stripped.
* Aside from white space at the beginning and / or end, the actual string will be unaffected. This means too, though, that extraneous spaces within the string -- for instance, a mistaken double-space type -- will not be corrected.  
* Aside from white space at the beginning and / or end, the actual string will be unaffected. This means too, though, that extraneous spaces within the string -- for instance, a mistaken double-space type -- will not be corrected.  
* The following will remove all double spaces and leading and trailing spaces.
* The following will remove all doubled (or further multiplied), leading and trailing spaces with iterated [[llReplaceSubString]]:
<syntaxhighlight lang="lsl2">llDumpList2String(llParseString2List(src, [" "], []), " "); //works but can use a large quantity of memory</syntaxhighlight>
<syntaxhighlight lang="lsl2">
* [[llReplaceSubString]] is probably the easiest way to remove all spaces from a string:
while(llStringLength(s) != llStringLength(s = llReplaceSubString(s, "  ", " ", 0)));
s = llStringTrim(s, STRING_TRIM);
</syntaxhighlight>
* llReplaceSubString is also the easiest way to remove all spaces from a string:
<syntaxhighlight lang="lsl2">llReplaceSubString("some words to remove the spaces from", " ", "", 0);</syntaxhighlight>
<syntaxhighlight lang="lsl2">llReplaceSubString("some words to remove the spaces from", " ", "", 0);</syntaxhighlight>
* An old method to strip spaces from the sentence:
* [[llList2Json]] also trims strings contained in the list. Thus, an easy way to trim an entire list of strings is:
<syntaxhighlight lang="lsl2">
<syntaxhighlight lang="lsl2">
list l = ["  a  ", " b", "c ", " d "];
list trimmedList = llJson2List(llList2Json(JSON_ARRAY, l));
</syntaxhighlight>
* Some old, less efficient methods, no longer recommended for use:
:* Intra-string space trimming:
::<syntaxhighlight lang="lsl2">llDumpList2String(llParseString2List(src, [" "], []), " "); //works but can use a large quantity of memory</syntaxhighlight>
:* An method to strip spaces from the sentence:
::<syntaxhighlight lang="lsl2">
//Added By To-mos Codewarrior
//Added By To-mos Codewarrior
string str1 = "some words to remove the spaces from";
string str1 = "some words to remove the spaces from";
Line 93: Line 104:
}
}
</syntaxhighlight>
</syntaxhighlight>
* The following will do the same:
:* Variant of above:
<syntaxhighlight lang="lsl2">(string)llParseString2List(src, [" "], []); //works but can use a large quantity of memory</syntaxhighlight>
::<syntaxhighlight lang="lsl2">(string)llParseString2List(src, [" "], []); //works but can use a large quantity of memory</syntaxhighlight>
* [[llList2Json]] also trims strings contained in the list. Thus, an easy way to trim an entire list of strings is:
<syntaxhighlight lang="lsl2">
list l = ["  a  ", " b", "c ", " d "];
list trimmedList = llJson2List(llList2Json(JSON_ARRAY, l));
</syntaxhighlight>
|deprecated
|deprecated
|cat1=String
|cat1=String

Latest revision as of 10:19, 13 January 2025

Summary

Function: string llStringTrim( string src, integer type );
0.0 Forced Delay
10.0 Energy

Returns a string that is src with leading and/or trailing white space (spaces, tabs, and line feeds) trimmed from it.

• string src
• integer type STRING_TRIM* flag(s)

Constant Description
STRING_TRIM_HEAD 0x1 Trims white space off the beginning.
STRING_TRIM_TAIL 0x2 Trims white space off the end.
STRING_TRIM 0x3 Trims white space off the beginning and end.

Examples

Whenever you are accepting unstructured input from a user -- whether via chat or via a notecard -- it is a good idea to always full trim it:

llStringTrim("User input", STRING_TRIM);

This example returns the number of leading and trailing 'white space' characters on a string that were removed (not particularly useful but shows how to use the function).

default
{
    state_entry()
    {
        llListen(4, "", llGetOwner(), "");
    }

    on_rez(integer start_param)
    {
        llResetScript();
    }

    listen(integer channel, string name, key id, string message)
    {       
        //track the length
        integer length = llStringLength(message);
        
        //trim message (not necessary to store these to variables but makes reading easier)
        string trim_left  = llStringTrim(message, STRING_TRIM_HEAD);
        string trim_right = llStringTrim(message, STRING_TRIM_TAIL);
        string trim_both  = llStringTrim(message, STRING_TRIM);

        //output the results
        llOwnerSay("Initial length  = " + (string)length +
                 "\nLeading Spaces  = " + (string)(length - llStringLength(trim_left))+
                 "\nTrailing Spaces = " + (string)(length - llStringLength(trim_right))+
                 "\nTrimmed Message = \"" + trim_both + "\"");
    }
}

Notes

  • The exact set of characters stripped are 0x09 (tab), line feed (0x0a, "\n"), vertical tab (0x0b), form feed (0x0c), carriage return (0x0d) and space (0x20, " ").
    • Only line feed and space function as true whitespace within SL, the others will produce some manner of a printable character.
    • The "\t" escape code doesn't actually represent the tab character, but several spaces instead.
    • Other whitespace characters defined in Unicode, such as non-breaking space (0xa0) or specific-width spaces in the 0x2000 range are not stripped.
  • Aside from white space at the beginning and / or end, the actual string will be unaffected. This means too, though, that extraneous spaces within the string -- for instance, a mistaken double-space type -- will not be corrected.
  • The following will remove all doubled (or further multiplied), leading and trailing spaces with iterated llReplaceSubString:
while(llStringLength(s) != llStringLength(s = llReplaceSubString(s, "  ", " ", 0)));
s = llStringTrim(s, STRING_TRIM);
  • llReplaceSubString is also the easiest way to remove all spaces from a string:
llReplaceSubString("some words to remove the spaces from", " ", "", 0);
  • llList2Json also trims strings contained in the list. Thus, an easy way to trim an entire list of strings is:
list l = ["  a  ", " b", "c ", " d "];
list trimmedList = llJson2List(llList2Json(JSON_ARRAY, l));
  • Some old, less efficient methods, no longer recommended for use:
  • Intra-string space trimming:
llDumpList2String(llParseString2List(src, [" "], []), " "); //works but can use a large quantity of memory
  • An method to strip spaces from the sentence:
//Added By To-mos Codewarrior
string str1 = "some words to remove the spaces from";
integer index;
while(~index=llSubStringIndex(str1," ")) {
    data=llDeleteSubString(str1,index,index);
}
  • Variant of above:
(string)llParseString2List(src, [" "], []); //works but can use a large quantity of memory

Deep Notes

History

  • Introduced in 1.13.4
Date of release 25-04-2007

Signature

function string llStringTrim( string src, integer type );