Analysing And Detecting Of Logical Expression Likely Invariant

The computer software system has been more and more popular and important today, so the quality of software has been a significant and hot issue. In order to improve software quality, DBC (Design By Contract) has been developed. Contracts describe properties, expectations and guarantees of a program. Program invariant, which includes class invariants, pre-condition and post-condition, is a common kind of contracts.In this paper, the type of logical expression likely invariant is presented through analysing, a theory model for dynamically generating likely invariant is built. The dynamical generating technique of likely program invariant is discussed. Furthermore, a new method of dynamically generating logical expression likely invariant is presented. The method, which comprises of series of detecting measures of specific logical expression likely invariants by using SQL query, takes the advantage of database. So, we can dynamically discover any kind of logical expression likely invariants by giving the query conditions.Finally, a prototype system for dynamically generating likely invariant is analyed and designed. The system has two excellent features. First, it is expansible; second, it can detect likely invariants in a nimble way.