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How to debug your code

From Joomla! Documentation

Revision as of 05:23, 25 August 2011 by Jonasfh (Talk | contribs)

The Easy Way: The simplest way to see what is going on inside your code is to temporarily add echo statements for variables to show their values on the screen. For example, say you want to know what the value of some variables are when $i is "5". You could use code like this:

for ( $i = 0; $i < 10; $i++ ) {
        if ( $i == 5 ) {
                echo '$i=' . $i; 
                // other echo statements 
        }
}

This works for simple situations. However, if you are planning on doing a lot of Joomla! development, it is worth the effort to install and learn an integrated development environment (IDE) that includes a real PHP debugger.

Using an IDE: Many Joomla! developers use the Eclipse IDE. This is free and includes a debugger. Instructions for installing it are available at Setting_up_your_workstation_for_Joomla!_development.

Using the PHP Expert editor: Another option is the PHP Expert editor with an installed extension for debugging. Add the following lines to the php.ini file:

extension=php_dbg.dll
[Debugger]
debugger.enabled=on
debugger.profiler_enabled=off

It is best to set profiler_enable to "off". Then you need set options in the menu Run/Options menu to use HTTP-server and the directory to where your script is located.

If all options are correct you may run your script in debug mode by clicking on the Debug button (F8).

J!Dump: An often handy extension that can be found in the JED is the J!Dump extension that will allow you to dump variable, stack traces, and system information into a popup window at run time. This extension works similarly to the php command `var_dump` but formats the output in a much more readable fashion.

JDEBUG To check if the website is beeing debugged, you test the JDEBUG - variable:

if(JDEBUG){
//whatever debugging code you want to run
}