On Apr 17, 2011, at 14:08, JAMES ROGERS wrote:

> I have stepped this through with the debugger and no flags were raised. The 
> code compiles without an error or a warning of any kind. I am afraid your 
> response has overwhelmed me.
> 
> One thing I will mention,  I am not changing string. So that point is a moot 
> one. I am just copying data out of the string.
> 
> The "substring = [NSString stringWithUTF8String:sndBuffer]" was not my own 
> and came from a website as a result of my query on "C string to NSString" and 
> it works.

Sorry, didn't mean to be overwhelming. :)

Yes, the compiler is no help to you here. Testing might not show a problem 
either. If your text view happens to contain only ASCII characters (which are 
represented by a single element in both UTF-8 and UTF-16, and which fit in an 
8-bit 'char'), you won't see a problem.

Here's how to change your code to avoid the 8-bit vs 16 bit and UTF-8 vs UTF-16 
problem:

> unichar sndBuffer[65];
> int j;
> 
> characterIndex++;  // is always sitting at the last character sent so advance 
> to the next character in string.
> for (j = 0; j < 65; j++) {
>    sndBuffer[j] = [string characterAtIndex:characterIndex];
>    characterIndex++;
> }
> 
> substring = [NSString stringWithCharacters:sndBuffer length:j];

Or, more compactly as Mike suggested:

> int length = MIN ([string length] - characterIndex, 65);
> substring = [string substringWithRange: NSMakeRange (characterIndex, length)];
> characterIndex += length;

However, neither version solves the problem of breaking off in the middle of a 
multi-element UTF-16 sequence.

Incidentally, looking at your original code again, it sure looks like 
'characterIndex' is getting over-incremented. You're going to skip over the 
first character of every substring. Shouldn't it be:

> unichar sndBuffer[65];
> int j;
> 
> for (j = 0; j < 65; j++)
>    sndBuffer[j] = [string characterAtIndex:++characterIndex]; // is always 
> sitting at the last character sent so advance to the next character in string.
> 
> substring = [NSString stringWithCharacters:sndBuffer length:j];


?

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