Debuggers

Anyone learning programming will undoubtedly come across the term ‘debugging’ sooner or later. This process refers to a complete check of the source code of a computer program, which aims to uncover any errors contained in the code. If you want your developed software to work as intended on all target platforms and devices, using a debugger will be absolutely essential. In the following article, you’ll learn what a debugger is, how these useful programs work, and where they are typically used.

A debugger is a computer program that allows you to uncover and diagnose errors in computer software. The aim of debugging tools is to ensure the long-term functionality of the given software on all intended devices and platforms. For this reason, many debuggers not only examine the respective source code but also the interaction with the executing operating system and underlying hardware. The debugging process takes place during runtime, meaning the software does not need to be closed down for the check.

Debugging contains ‘bug’ because this word has been used for decades to describe all sorts of programming errors in software development. Engineers even called malfunctions ‘bug’ as early as the 19th century. Based on this term, a solution to a software error is said to be a ‘bugfix’.

There is no such thing as perfect software without bugs. Daily optimisation is therefore indispensable. Here, the big problem often lies not in finding faulty processes in the programming sequence, but in determining their exact cause. Even just a mispositioned bracket or an incorrectly used operator can result in a program no longer functioning properly. In the case of hundreds or even thousands of lines of code, manual searches performed row by row offer little prospect of success. For this reason, modern debugging tools not only provide information that a problem has been determined, but also offer extensive details on the type of error and which code lines contain the error.

Normally, debuggers work through the program code in a step-by-step manner. Breakpoints are, therefore, defined in the software to be debugged. The debugging tool recognises these breakpoints and can use them to stop running the software at exactly these points. For developers, this opens up the following two possibilities:

• It is possible to examine the exact state of the program at this time. For instance, it is easy to check whether all integrated variables have output the expected values.
   
• It is possible to play the program from the respective breakpoint to delineate any problems or sources of errors.

The breakpoints do not need to be fixed. Many debuggers allow breakpoints to be tied to individual conditions. This way, the program can stop under certain circumstances. For example, if a loop undergoes 20 passes correctly and only encounters a program error on the 21st pass, the debugger can launch directly into the problem case thanks to a corresponding condition. In other words, the previous incident-free passes do not need to be repeated.

The other functions of debuggers include the inspection of data, such as the content of variables, repositories or registers, as well as the modification of memory, such as the main storage (working memory) or the processor register.

How exactly a debugger can be used for troubleshooting in software depends on the tool itself as well as the operating system the software (and bugger) are running on. As the user, you tell the troubleshooting tool which process it should connect with – either with a process ID or a name. In the case of the latter, the debugger initially finds out the associated process ID. Next, a system request initiates the debugging session.

In general, there are two approaches for the use of debugging tools:

• The troubleshooting process is performed within the system a software runs on.
   
• The troubleshooting process is not launched on the computer the software runs on. Instead, it is initiated by a remote system – this is called remote debugging.

Modern debuggers are often able to take into account changes to the source code of a software during execution. Known as just-in-time debugging, this is especially popular during the early development phase of a computer software, where minor and major code errors are by no means uncommon. It is not without reason that the development environments of a wide range of script languages and frameworks also feature an integrated debugger.

When it comes to debuggers or debugging in general, if computer code is to work as flawlessly as possible for the long-term, running a troubleshooting process becomes indispensable – no matter whether you want to program, further develop or test a simple script, a single process, a module, a complex program or a complete operating system.

In the case of non-programmers, it is beneficial if a software features a suitable debugger. When designed and configured appropriately, the tool can act like a mouthpiece between program users and developers in the event of errors during use. Thanks to debugging reports, the developers can more easily reproduce the error and determine how the user can solve the problem with the software. Depending on the program, debugger, and severity of the error, an integrated debugging tool can even allow users of a software program to carry out troubleshooting on their own.