Using 0 as a special error value is a kind of a hack though. What you're really doing is returning "either an error or an index", which is a different type than

Using 0 as a special error value is a kind of a hack though. What you're really doing is returning "either an error or an index", which is a different type than "an index". Empirically, using one language type for two concepts like this, allowing errors to be silently dropped as values can be implicitly converted from one to the other, has been very error prone. See the discussions about nullable pointers for example. WRT strings with metadata, if you construct your data structure so that the length and other metadata are at negative offsets from the pointer value that gets passed around, then the array data can be at offset zero again, so it's even more efficient. So zero still wins :). But the arguments for 0-based indexing are also deeper than C arrays. C arrays are just one place where it's clearly visible. The Pascal approach unfortunately doesn't solve the problem either. "Everyone can do what they like" is fine as long as no one ever has to read or interface with code written by other people.