Package 'sfsmisc'
has a function AsciiToInt() and a few useful related "R-code"
only functions such as chars8bit(); see the help pages once
you've installed and attached the package.
But do note that these things do depend on the encoding, as Uwe
Ligges has already told you.
Things work fine for pure ASCII {independently of encoding}
but already differ for Umlauts / Accents
between iso-latin-1 or Unicode.
Martin Maechler, ETH Zurich