1. A method of declaring and using variables, the method comprising: determining whether variables are independent variables independently used by a plurality of processors or common variables commonly used by the plurality of processors; declaring the independent variables and storing the independent variables in a plurality of data structures respectively corresponding to the plurality of processors; declaring the common variables and storing the common variables in a shared memory area; allowing each one of the plurality of processors to simultaneously use the independent variables in a corresponding one of the plurality of data structures; and allowing only one of the plurality of processors at a time to use the common variables in the shared memory area, wherein allowing each one of the plurality of processors to simultaneously use the independent variables in a corresponding one of the plurality of data structures comprises transferring independent variables stored in one of the plurality of data structures to a cache corresponding to one of the plurality of processors accessing the one of the plurality of the data structures, and wherein a size of the one of the plurality of data structures matches a size of one or more data segment in the cache.