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Evaluate Variables in QtScript

I am looking for a way to find out the variables in a script (QtScript).
An example would be this formula:
@c = a + b + 15@The variables I would like to find is a, b and c.
Can someone give me a hint with this?

I think you are looking for how to solve an equation using JavaScript  something very different from evaluating script, such as the QtScript engine does.
The problem you pose has more than one solution as well, as you can see here: "Wolfram Alpha":http://www.wolframalpha.com/input/?i=c+=+a+++b+++15 (sorry you have to enter the equation again as this forum destroys it).
Some solutions for your equation would be
25 = 5 + 5 + 15
35 = 10 + 10 + 15and so on.

Thanks for your input, but my equation was just a sample.
What I want is as example to load this equation from a file, but I would like to find out the used variables before putting it into the script engine.

Hello,
OK now I get it  you are not looking for variable values but variable names.
Do you have a realworld example of what you want to achieve?

I do not have a real world example, but I try to explain it more global.
Let's assume I can get scriptcode in several ways (file, tcp, ...) and I want to execute this code in the script engine. Before executing the code I would like to get somehow a list of used variables.
The question is now, how to get the list of variables?

Parse the code. Either with an own parser or by using some ECMAScript parser library. Maybe you can somehow rip out the parsing code of the QtScript module.

Okay, but it seems there is no way that the QtScript could do this?