Trying to choose a "special character" to use as a flag. How can you compare to a special character?

[Love Zhaoying]

I need to choose a "relatively unused" special character that I can use as a "flag" in messages sent between my scripts.

I've been studying the use of UTF-8 via llUnescapeURL(), etc.

From this, I had the idea that I could perhaps use a UTF-8 character..

However, how would I compare for it?

Idea: Can you compare two strings that have the same special UTF-8 value?

For instance, I could use the Chr() function from the library (http://wiki.secondlife.com/wiki/Chr) to encode 0x2665 as the "heart" character and save that in a string variable:

   string sHeart=Chr(0x2665);

a)  Is it then valid to compare this using normal string methods? For example:

  if (llSubStringIndex(otherstring, sHeart)==0) // Found heart at the start!

b) Can you suggest another way to do this without having to use the Chr() functions to "build" the character into a string in the first place?

Thanks!

 

[Rolig Loon]

That certainly works.  The best way to tell, of course, is to try it yourself...

// Chr() function, written by Pedro Oval, 2010-05-28 // Auxiliary function UrlCode, which returns the hex code of the given integer// (which must be in range 0-255) with a "%" prepended.string UrlCode(integer b){    string hexd = "0123456789ABCDEF";    return "%" + llGetSubString(hexd, b>>4, b>>4)               + llGetSubString(hexd, b&15, b&15);} // Chr function itself, which implements Unicode to UTF-8 conversion and uses// llUnescapeURL to do its job.string Chr(integer ord){    if (ord <= 0)        return "";    if (ord < 0x80)        return llUnescapeURL(UrlCode(ord));    if (ord < 0x800)        return llUnescapeURL(UrlCode((ord >> 6) | 0xC0)                            +UrlCode(ord & 0x3F | 0x80));    if (ord < 0x10000)        return llUnescapeURL(UrlCode((ord >> 12) | 0xE0)                            +UrlCode((ord >> 6) & 0x3F | 0x80)                            +UrlCode(ord & 0x3F | 0x80));    return llUnescapeURL(UrlCode((ord >> 18) | 0xF0)                        +UrlCode((ord >> 12) & 0x3F | 0x80)                        +UrlCode((ord >> 6) & 0x3F | 0x80)                        +UrlCode(ord & 0x3F | 0x80));}string heart;string test;default{    state_entry()    {        heart = Chr(0x2665);        test = "This string contains a "+heart+ " in it.";    }        touch_start(integer num)    {        integer idx = llSubStringIndex(test,heart);        if (~idx)        {            llSay(0,heart + " is at position " + (string)idx);        }    }}

which returns

Test Object: ♥ is at position 23

Other than the novelty of using a character like ♥, however, I can't see a particular advantage of going to all this trouble.  Personally, I'd just stick with the character set on the keyboard if all I needed was a flag.  But that's just me.

[Love Zhaoying]

Thanks, I have ideas at my office when I can't try them. 

The reason I want a "special" character is, to be a real and true "flag" I have to choose something that can't be part of normal data.  This is because I am coding something that needs to be able to handle any value for the data (for strings at least). The "heart" was just an example I chose from the link.  If it were me, I would choose an odd ASCII character but I haven't figured out if those are actually available, or not available for use in LSL. 

The fact that only a few "special characters" are defined under "escape codes" (tab, newline, double quote, backslash) and I could not find any examples of using "control characters" (low/high ASCII) let me to think that the UTF-8 is the best chance at a "flag" that I will get: the point being to select a character that will almost definitely never be part of the data; I can select some strange symbol that is hopefully ugly enough noone will choose it on purpose. But, I'll make it "changeable" in my code just in case.

Thanks, as always!

 

 

[Love Zhaoying]

I was happy to find I can post ♥ or whatever UTF-8 character directly into LSL code, so I won't need the chr() function for my purposes. Yay!