We provide a verification technique for a class of programs working  on \emph{integer
arrays} of finite, but not a priori bounded length. We use the logic of integer arrays \textbf{SIL} \cite{lpar08} to
specify pre- and post-conditions of programs and their parts. Effects of non-looping parts of code are computed
syntactically on the level of \textbf{SIL}. Loop pre-conditions derived during the computation in \textbf{SIL} are
converted into counter automata (CA). Loops are automatically translated---purely on the syntactical level---to
transducers. Pre-condition CA and transducers are composed, and the composition over-approximated by flat automata with
difference bound constraints, which are next converted back into \textbf{SIL} formulae, thus inferring post-conditions
of the loops. Finally, validity of post-conditions specified by the user in \textbf{SIL} may be checked as entailment is
decidable for \textbf{SIL}.