String problem

I've hit a bit of a snag in my program. My string is terminating at the wrong point but I'm not sure why. I'm building my string up from several compressed numbers, using a small compression routine, which I'm certain is fine because I took it from the Blitzplay library.

When I follow it through on the debugger, I can see the little strings being built up - for example, they'll show 'A', then 'A^', then 'A^f'. The quotation marks are clear around the string as it builds up. But when I put a certain number into the function, it shows 'Me .... but no closing quotation mark. Then when I add that string to the bigger string, the big string also terminates at that point, and adding anything else to it seems to make no difference (it does seem to get longer, but I can't see anything after that point).

The function is as follows.

Function IntToStr$(Num%,StrLen%=4)
;-=-=-=Take an Integer and compress it to a string, of "strlen" bytes long.
	Local shiftin%
	Local st$=Chr$(num And 255)
	For shiftin=1 To (strlen-1)
		st$=st$+Chr$(num Sar(8*shiftin))
	Next
	Return st$
End Function

It goes wrong when the number 25933 is put into it.

Any ideas? I'm guessing I'm making some really obvious mistake here :(

I see no problem with -

For NumLoop=25000 To 25001
	Compre$=IntToStr(NumLoop,4)
	Concat$=ConCat$+Compre+";"
Next
Print ConCat$
Print Len(ConCat)

ConCat=""

For NumLoop=25933 To 25934
	Compre$=IntToStr(NumLoop,4)
	Concat$=ConCat$+Compre+";"
Next
Print ConCat$
Print Len(ConCat)

WaitKey

End



Function IntToStr$(Num%,StrLen%=4)
;-=-=-=Take an Integer and compress it to a string, of "strlen" bytes long.
	Local shiftin%
	Local st$=Chr$(num And 255)
	For shiftin=1 To (strlen-1)
		st$=st$+Chr$(num Sar(8*shiftin))
	Next
	Return st$
End Function

Ah, it's a problem with the debugger then. If you follow your program through line-by-line, you'll see that it doesn't update the string properly as it goes along, although it does print them out properly. Strange.

It does seem to be causing errors in my server/client though, because it doesn't seem to want to send the string after that point :(

Bump.

Can someone run the above program and watch it with the debugger? Can you explain why, when it's building up the number 25933 the string suddenly has no terminating "? Is this just a printing error in the debugger, or is something else going on here?

It's causing a major headache for me now, because once I add that string to my longer string, anything else I add is ignored by my network library.

Converting this line

st$=st$+Chr$(num Sar(8*shiftin))

into steps shows better what's going on:

Stop
For NumLoop=25000 To 25001
	Compre$=IntToStr(NumLoop,4)
	Concat$=ConCat$+Compre+";"
Next
Print ConCat$
Print Len(ConCat)

ConCat=""

For NumLoop=25933 To 25934
	Compre$=IntToStr(NumLoop,4)
	Concat$=ConCat$+Compre+";"
Next
Print ConCat$
Print Len(ConCat)

WaitKey

End



Function IntToStr$(Num%,StrLen%=4)
;-=-=-=Take an Integer and compress it to a string, of "strlen" bytes long.
	Local shiftin%
	Local st$=Chr$(num And 255)
	For shiftin=1 To (strlen-1)
		temp = 8*shiftin
		temp2 = num Sar(temp)
		temp3$ = Chr$(temp2)
		st$ = st$ + temp3$
		;st$=st$+Chr$(num Sar(8*shiftin))
	Next
	Return st$
End Function

You see, you are adding a chr$(0), which is NULL. That's why the IDE doesn't display it correctly.

Heres one explanation:
http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:47238880219973

And an ASCII table:
http://www.neurophys.wisc.edu/www/comp/docs/ascii.html

Thanks, that explains that then.

Leaves me with two options. One is to use Bitstreams for my library, which might be better but will need more converting. Two, is to change the IntToStr (and it's opposite StrToInt) so that it doesn't use anything between 0-31. Does anyone know how I'd do that?