Lear No Degub

debug Learn to Debug Debugging is the cornerstone of being a programmer. The first meaning of the verb to debug is to remove errors, but the meaning that really matters is to see into the executionof a program by examining it. A programmer that cannot debug effectively is blind. Idealists that think design, or analysis, or complexity theory, or whatnot, are more fundamental are not workingprogrammers. The working programmer does not live in an ideal world. Even if you are perfect, your are surrounded by and must interact with code written by major software companies, organizations like GNU,and your colleagues. Most of this code is imperfect and imperfectly documented. Without the ability to gain visibility into the execution of this code the slightest bump will throw you permanently.Often this visibility can only be gained by experimentation, that is, debugging. Debugging is about the running of programs, not programs themselves. If you buy something from a major software company,you usually don't get to see the program. But there will still arise places where the code does not conform to the documentation (crashing your entire machine is a common and spectacular example), orwhere the documentation is mute. More commonly, you create an error, examine the code you wrote and have no clue how the error can be occurring. Inevitably, this means some assumption you are makingis not quite correct, or some condition arises that you did not anticipate. Sometimes the magic trick of staring into the source code works. When it doesn't, you must debug. To get visibility into theexecution of a program you must be able to execute the code and observe something about it. Sometimes this is visible, like what is being displayed on a screen, or the delay between two events. Inmany other cases, it involves things that are not meant to be visible, like the state of some variables inside the code, which lines of code are actually being executed, or whether certain assertions...