Quote:Notice: undefined index:supplement_id in .....cart.php on line 27
First of all, it is a good idea to give exact error message.
Then if code snipset don't start at beginning of file, it is also a good idea to tell where is the offending line in snipset.
Quote:Notice: undefined index:supplement_id
No matter what is the exact problem, this means that your code try to read a position that does not exist in the array.
The only thing to do is to launch the debugger and inspect the variable when error is thrawn again. We have no way to guess what is going on.
Your code do not behave the way you expect, or you don't understand why !
There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your code is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.
Debugger - Wikipedia, the free encyclopedia
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide
Basic Debugging with Visual Studio 2010 - YouTube
phpdbg | php debugger
Debugging techniques for PHP programmers
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.