The Xcdb debugger

Xcdb is a graphically-oriented symbolic debugger for C, C++, and FORTRAN programs running under AIX Version 3, Release 2 (and later). It is a standalone program, not a windowed frontend to dbx. Xcdb has the breakpointing, stepping, and traceback capabilities common to most debuggers, but particular attention has been paid to presentation and ease of use. Xcdb understands the name mangling schemes used by xlC for typesafe linkage. It can display C++ class objects, display and set breakpoints in template instantiations, and display the internal contents of virtual function tables.

Xcdb runs under the X windowing system and makes full use of X capabilities. Because Xcdb runs in an X window separate from the program being debugged, each has unrestricted use of the screen, mouse, and keyboard. The debugger is mouse driven, which means that most interactions are performed by positioning the mouse over an appropriate screen location and clicking a key or button. Xcdb requires little or no typing.

Significant features

With Xcdb, you can:

Inspect the local environment of any function in the call chain and display the format (signed, unsigned, hex, etc.) of any individual variable.
Expand aggregate objects (classes, structs, unions, and arrays) to reveal arbitrary levels of detail.
Tailor window layout to your preferences by making appropriate entries in your .Xdefaults file.
Dereference pointers to reveal pointed-to objects.
Obtain the type, size, and address of any object.
Call upon C++ class instances to display themselves.

NOTE

See "Frequently asked questions" on page 138 for questions and answers about Xcdb topics.

When Xcdb traps a program interruption, either planned (by setting breakpoints) or unplanned (due to program exceptions or external signals), Xcdb makes the program state available for inspection. The display includes window panes for:

A traceback of uncompleted function calls
A view of the source code for the current function, positioned at the current line
A view of variables defined in the scope of the current function
A view of variables defined outside the scope of any function

If the program interruption is of a type that allows execution to be continued, then you can resume program execution, perhaps after setting or clearing breakpoints. You can either ignore the signal that caused the interruption or pass it to the program.

Here is a typical display following a program exception.

Significant features
The Xcdb setup
Running Xcdb
Window organization
Window manipulation
Execution control
Format control
Breakpoints
Preferences
Self-displaying C++ objects
Customizing Xcdb
Frequently asked questions
Reporting bugs

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