7.10 Electronic Archaeology

Unfortunately, most programmers don't start a project at the design step. Instead they are immediately thrust into the maintenance or revision stage. This means most programmers are faced with the worst possible job: understanding and modifying someone else's code.

Contrary to popular belief, most C++ programs are not written by disorganized orangutans using Zen programming techniques and poorly commented in Esperanto. They just look that way. Electronic archeology is the art of digging through old code to discover amazing things (like how and why the code works).

Your computer can aid greatly in your search to discover the true meaning of someone else's code. Many tools are available for examining and formatting code. Some of these tools include:

Cross-referencers

These programs have names like xref, cxref, and cross. System V Unix has the utility cscope. They print out a list of variables and where the variables are used.

Program indenters

Programs such as cb and indent indent a program "correctly" (correct indentation is something defined by the tool maker).

Pretty printers

A pretty printer such as vgrind or cprint typesets source code for printing on a laser printer.

Call graphs

On System V Unix, the program cflow analyzes the structure of a program. On other systems there is a public domain utility, calls, that produces call graphs, showing who calls whom and who is called by whom.

Class browsers

A class browser allows you to display the class hierarchy so you can tell what components went into building the class, as well as its structure. You'll learn what a class is in Chapter 13.

IDEs

Both Borland-C++ Builder and Microsoft Visual C++ .NET contain an integrated development environment (IDE). This means that the tool has both an editor and source browsing tools built in. Commercial and free IDEs are available for Unix as well. One of the better free ones is Source Navigator, which can be obtained from http://sources.redhat.com/sourcenav (Appendix E gives the location of this and many other freely available tools).

Which tools should you use? Whichever ones work for you. Different programmers work in different ways. Some techniques for examining code are listed in the following sections. Choose the ones that work for you and use them.