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copied!<p>Actually you have quite a lot of possibilities. Either with recompilation of source code or without.</p> <h2>With recompilation.</h2> <ul> <li>Additional <a href="http://en.wikipedia.org/wiki/Computer_data_logging" rel="nofollow noreferrer">logging</a>. Either into program's logs or using system logging (eg. OutputDebugString or Events Log on Windows). Also use following steps: <ul> <li>Always include timestamp at least up to seconds resolution.</li> <li>Consider adding thread-id in case of multithreaded apps.</li> <li>Add some nice output of your structures</li> <li>Do not print out enums with just %d. Use some <code>ToString()</code> or create some <code>EnumToString()</code> function (whatever suits your language)</li> <li>... and beware: logging <strong>changes</strong> timings so in case of heavily multithreading you problems might disappear.</li> <li>More details on this <a href="https://stackoverflow.com/questions/1592457/how-you-can-debug-a-program-without-a-debugger/1592463#1592463">here</a>.</li> </ul></li> <li>Introduce more asserts</li> <li>Unit tests</li> <li><em>"Audio-visual"</em> monitoring: if something happens do one of <ul> <li>use buzzer </li> <li>play system sound </li> <li>flash some LED by enabling hardware GPIO line (only in embedded scenarios) </li> </ul></li> </ul> <h2>Without recompilation</h2> <ul> <li>If your application uses network of any kind: <a href="http://en.wikipedia.org/wiki/Packet_analyzer" rel="nofollow noreferrer">Packet Sniffer</a> or I will just choose for you: <a href="http://www.wireshark.org/" rel="nofollow noreferrer">Wireshark</a></li> <li>If you use database: monitor queries send to database and database itself.</li> <li>Use virtual machines to test exactly the same OS/hardware setup as your system is running on.</li> <li>Use some kind of system calls monitor. This includes <ul> <li>On Unix box <a href="http://en.wikipedia.org/wiki/Strace" rel="nofollow noreferrer">strace</a> or <a href="http://en.wikipedia.org/wiki/DTrace" rel="nofollow noreferrer">dtrace</a></li> <li>On Windows tools from former <a href="http://technet.microsoft.com/en-us/sysinternals/default.aspx" rel="nofollow noreferrer">Sysinternals</a> tools like <a href="http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx" rel="nofollow noreferrer">http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx</a>, <a href="http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx" rel="nofollow noreferrer">ProcessExplorer</a> and alike</li> <li>In case of Windows GUI stuff: check out <a href="http://msdn.microsoft.com/en-us/library/aa264396%28VS.60%29.aspx" rel="nofollow noreferrer">Spy++</a> or for WPF <a href="http://blois.us/Snoop/" rel="nofollow noreferrer">Snoop</a> (although second I didn't use)</li> <li>Consider using some profiling tools for your platform. It will give you overview on thing happening in your app.</li> </ul></li> <li><strong>[Real hardcore]</strong> Hardware monitoring: use oscilloscope (aka O-Scope) to monitor signals on hardware lines</li> <li>Source code debugging: you sit down with your source code and just pretend with piece of paper and pencil that you are computer. Its so called code analysis or "on-my-eyes" debugging</li> <li>Source control debugging. Compare diffs of your code from time when "it" works and now. Bug might be somewhere there. </li> </ul> <p>And some general tips in the end:</p> <ul> <li>Do not forget about <em>Text to Columns</em> and <em>Pivot Table</em> in Excel. Together with some text tools (<code>awk</code>, <code>grep</code> or <code>perl</code>) give you incredible analysis pack. If you have more than 32K records consider using Access as data source.</li> <li>Basics of <a href="http://en.wikipedia.org/wiki/Data_warehouse" rel="nofollow noreferrer">Data Warehousing</a> might help. With simple cube you may analyse tons of temporal data in just few minutes.</li> <li>Dumping your application is worth mentioning. Either as a result of crash or just on regular basis</li> <li><strong>Always</strong> generate you debug symbols (even for <a href="https://stackoverflow.com/questions/420343">release builds</a>).</li> <li>Almost last but not least: most mayor platforms has some sort of command line debugger always built in (even Windows!). With some tricks like conditional debugging and break-print-continue you can get pretty good result with obscure bugs</li> <li>And really last but not least: use your brain and <strong>question everything</strong>.</li> </ul> <p>In general debugging is like science: you do not create it you discover it. Quite often its like looking for a murderer in a criminal case. So buy yourself <a href="http://images.google.com/images?client=safari&rls=en&q=sherlock+holmes+hat&oe=UTF-8&um=1&ie=UTF-8&ei=2EjdSsr_F8P54AbugOkK&sa=X&oi=image_result_group&ct=title&resnum=1&ved=0CBYQsAQwAA" rel="nofollow noreferrer">a hat</a> and never give up.</p>

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