We present a modular analysis able to tackle out-of-bounds accesses in C strings. This analyzer is modular in the sense that it infers and tabulates (for reuse) input/output relations, automatically partitioned according to the shape of the input state. We show how the inter-procedural iterator discovers and generalizes contracts in order to improve their reusability for further analysis. This analyzer was implemented and was able to successfully analyze and infer relational contracts for functions such as strcpy, strcat.