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I'm trying to demonstrate invariants in Code Contracts, and I thought I'd give an example of a sorted list of strings. It maintains an array internally, with spare space for additions etc - just like List<T> , basically. When it needs to add an item, it inserts it into the array, etc. I figured I had three invariants: The count must be sensible: non-negative and at most as big as the buffer size Everything in the unused part of the buffer should be null Each item in the used part of the buffer should be at least as "big" as the item before it Now, I've tried to implement that in this way: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(count >= 0 && count <= buffer.Length); for (int i = count; i < buffer.Length; i++) { Contract.Invariant(buffer[i] == null); } for (int i = 1; i < count; i++) { Contract.Invariant(string.Compare(buffer[i], buffer[i - 1]) >= 0); } } Unfortunately, ccrewrite is messing up the loops. The user documentation says that the method should just be a series of calls to Contract.Invariant . Do I really have to rewrite the code as something like this? Contract.Invariant(count >= 0 && count <= buffer.Length); Contract.Invariant(Contract.ForAll (count, buffer.Length, i => buffer[i] == null)); Contract.Invariant(Contract.ForAll (1, count, i => string.Compare(buffer[i], buffer[i - 1]) >= 0)); That's somewhat ugly, although it does work. (It's much better than my previous attempt, mind you.) Are my expectations unreasonable? Are my invariants unreasonable? (Also asked as a question in the Code Contracts forum . I'

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