If you are CERTAIN that "lnlocation" is not accessed directly anywhere in the called method
you could also

loStringBuilder.Append(tcSearchIn, lnLocation, 1)
' System.Threading.Interlocked.Increment(lnLocation), 1)
lnLocation = lnLocation + 1

If you don't view/interpret pre/post-incrementing as "functions" in themselves you will run into trouble in complex lines <g>. The code *probably* needs only the above - you would have to ask the author of the original code or read a bit there...

regards

thomas