Lou Montana/Sandbox – User

Template:SideTOC Debugging Techniques are ways in which developers can debug, or find out where errors or unexpected outcomes are occurring within their scripts.

Code

Various links about code and how to write it:

• SQF syntax
• SQS syntax
• Code Optimisation

IDE and Syntax Highlight

Syntax errors can be a frequent occurrence when developing scripts. Syntax highlight will help you find typos in commands and in your scripts.
An Integrated Development Environment, shortened to IDE is as its name says a development environment program, providing syntax highlight helping you writing code.

See further Downloadable Tools page section for download links.

Finding Errors

To solve an issue, you must first find out there is one. Besides your script not having the wanted effect (if any), an error message helps you locate the code issue.

• Be sure to use -showScriptErrors startup parameter to display the error on-screen
• To ensure error location in your script, prefer preprocessFileLineNumbers to preprocessFile
• Read RPT files for more information (make sure -noLogs startup parameter is not enabled or the logs will never be filled)
  • Scripts running on a server use the ArmaXServer.RPT file which has varying locations depending upon the type of server being run.
  • Scripts running on a client use the ArmaX.RPT file.
  • RPT files location is usually %localappdata%\ArmaX

Removing Errors

Once the script error is located: be sure to check the BiKi page corresponding to the command/function you are using!!

ⓘ

If you're having great difficulty solving a problem, the good way is to bring the issue to the simplest code;

take the mission part that doesn't work, paste it into a new test mission and work from here.

Doing so will avoid you dealing with other scripts potential side effects!

Common errors

Error message	Cause	Solution
Error Undefined variable in expression: _varName	variable _varName has not been initialised properly in this context.	in the case of a spawned code, previous local variables are not accessible and must be passed as arguments in order to access them. a variable may have been undefined (_varName = nil). Unset it after you are done using it.
Error Zero divisor	Pretty self-explanatory, somewhere in your code is a division by zero.	* Make sure to check if your divisor is different from zero before dividing.
Generic error	Further code reading is required.	* If it happens on a sleep/uiSleep/waitUntil, you may be in unscheduled environment.

Working with Addons

If you are working on an addon, repacking a PBO can be time-intensive. This operation can be replaced simply by creating a basic mission in the "Missions" or "MPmissions" (if your feature is multiplayer-specific) folder of your game installation, and running the mission locally. The easiest way of accomplishing this is by the use of Event Scripts to run your code such as init.sqf. Once you have tested your code this way, you can then sequentially pack your PBO when major changes have been made, rather than for each debug session of a script or piece of code.

Debugging specific sections of code

Although primitive, the combined use of diag_log, systemChat/hint and format can help to debug the content of function arguments. In the case that specific pieces of code do not run, or if specific if conditions don't appear to fire, debugging the variable content with diag_log can be useful. As with all debugging, as long as the developer is methodical and logical in checking each section of code that runs, finding bugs and resolving them can be straightforward.

Downloadable Tools

IDE

• Sbsmac's Squint: Forum post - website
  Provides a fully-featured code editor which allows for syntax highlighting, displaying of errors and code correction.
• krzmbrzl's SQDev: Forum post - GitHub repository
  Provides code validation (linting) while you are typing it.

Syntax Highlight

• Sanjo's Notepad++ SQF (npp-sqf, plugin for Notepad++): Forum post - GitHub repository

Debug Console

A Debug Console is a powerful tool; it is very helpful at debugging your scripting in real time.

• Arma 3
  • The game already features Arma 3 Debug Console.
  • Charon Productions' TroopMon3 for Arma 3 (alpha)
• Take On Helicopters
  • The game already features TKOH Debug Console.
• Arma 2
  • Str's Debug console
  • Charon Productions' TroopMon3 for Arma 2 (TroopMon2 being obsolete and rewritten into this TroopMon3)
  • DevCon by Kju
• Arma
  • Charon Productions' TroopMon v0.8b - Complex debugging system providing lot of information for mission-makers, especially about AI.
  • Str's Debug Console - available in all singleplayer missions, intros and outros. Easy and simple to use (Escape-Enter execute)
• Operation Flashpoint
  • Vektorboson's Debug Console

Emulators and Debuggers

• X39's SQF VM - an SQF emulator
• Dedmen's Arma Script Profiler
• Dedmen's Arma Debug Engine