[Csnd-dev] strange string behaviour

due to strange problems with an old csd i came to this:

instr 1
   Snew = ""
   Sline = sprintfk("%s%d\n",Snew,1)
   Snew = strcatk(Snew,Sline)
   printf("Sline = \n%s\n",1,Sline)
   printf("Snew = \n%s\n",1,Snew)
   turnoff
endin
schedule(1,0,1)

i expect Sline to be 1 and Snew also.  but as printout shows:
Sline =
1
1
Snew =
1
1
1

am i doing something silly, or what is happening here?