Alter Xml File Without Xml Lib

[ThunderAI]

How would I go about changing an xml file with custom tags. All i want to do is open the file, change some numbers and save the file. I'd rather not make an XML scheme for the file and do it that way.

 

for example, I have a file with many tags like this:

 

<tag x="3364.994" y="599.9155" z="0.3324151" />

 

and I want to alter the x and y values based on some criteria.

 

What would be the best approach to do that?

 

Thanks.