read the value of each tag in xml file

Maybe you could be more precise in your question... From XML::Parser, I find:

    Parse will return a parse tree for the document. Each node in the 
+tree
    takes the form of a tag, content pair. Text nodes are represented 
+with a
    pseudo-tag of "0" and the string that is their content.
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So you get pairs of tag and content. What is the stumbling block for you to extract only the tag and ignore the content?