Executable Assertions - An Aid To Reliable Software

Two preprocessors, one for and one for have been implemented to allow "executable assertions" to be added to the source code. These assertions make it possible to carry out certain static and dynamic checks on the semantics of a program. They can detect errors in input data and prevent error propagation. It is possible to in clude remedial instructions to compensate for detected errors and provide fault tolerance. The assertions can be applied to all the data types available in the languages. Executable assertions can also be used in a proof of correctness. This paper describes the syntax of the assertions, which contain first-order logical expressions. Examples are given of their use in a simple but practical example, the calculation of the time that a ballistic projectile travels.