dbxtra tutorial session

Using a sample program, designed for bidding in the card game ``bridge'', we will explore some of the basic features of dbxtra.

The tutorial is organized as follows:

• ``Preparing files for dbxtra''

• ``Starting dbxtra''

• ``The dbxtra screen''

• ``The dbxtra help facility''

• ``Printing the value of variables''

• ``Viewing source code and aliasing''

• ``Viewing the call stack''

• ``Traversing the call stack''

• ``Monitoring the contents of variables''

• ``Analyzing the results''

• ``Examining a different function''

• ``Using a breakpoint''

• ``Continuing after a breakpoint''

• ``Exiting dbxtra''