Why Programs Fail: A Guide to Systematic Debugging is proof that debugging has graduated from a black art to a systematic discipline. It demystifies one of the toughest aspects of software programming, showing clearly how to discover what caused software failures, and fix them with minimal muss and fuss. The fully updated second edition includes 100+ pages of new material, including new chapters on Verifying Code, Predicting Erors, and Preventing Errors. Cutting-edge tools such as FindBUGS and AGITAR are explained, techniques from integrated environments like Jazz.net are highlighted, and all-new demos with ESC/Java and Spec#, Eclipse and Mozilla are included. This complete and pragmatic overview of debugging is authored by Andreas Zeller, the talented researcher who developed the GNU Data Display Debugger(DDD), a tool that over 250,000 professionals use to visualize the data structures of programs while they are running. Unlike other books on debugging, Zeller's text is product agnostic, appropriate for all programming languages and skill levels. The book explains best practices ranging from systematically tracking error reports, to observing symptoms, reproducing errors, and correcting defects. It covers a wide range of tools and techniques from hands-on observation to fully automated diagnoses, and also explores the author's innovative techniques for isolating minimal input to reproduce an error and for tracking cause and effect through a program. It even includes instructions on how to create automated debugging tools. The text includes exercises and extensive references for further study, and a companion website with source code for all examples and additional debugging resources is available.