Debugging run-time errors

The usual way of locating logical errors is to use a break-and-inspect-style debugging tool. The programmer uses the debugger to search for a small part of the program's execution that does not proceed as expected. Existing debuggers enable the programmer to make this search, but do not assist in the search. Techniques are presented for assisting the programmer in the error diagnosis process. A debugging tool incorporating these techniques assists the programmer in directing the course of the diagnosis, in determining which variables need to be examined at any breakpoint, in deciding whether the variables examined have the correct values, and in detecting the use of pointers to storage locations which have been previously released.>