Question

I have an XML file.

 <?xml version="1.0"?>
 <catalog>
    <book id="bk101">
    </book>
 <catalog>

I read the file and store it in file_data

 set data [split $file_data "\n"]
 foreach line $data {
 regexp { book id=\"(.*)\" } $line all dummy
 puts $all
 puts $dummy
 }

So here as you can see I am trying to read the book id and print it out.
I get the error dummy not found? Am I do it wrong?

Edit

Weirdly when I try this :

set mydata {<book id="bk101"> testing the code }
puts $mydata

regexp {book id="(.*)"} $mydata all part
puts $all
puts $part

Output

<book id="bk101"> testing the code
book id="bk101"
bk101

Have no idea the code at the top still shows error

Answer 1

The spaces in the RE are significant, and you place them around the original RE where there wouldn’t be any expected. If you want to parse XML though, it might be best to use tdom or TclXML.

You should check that the result of regexp returns a non-zero answer (meaning it found something), otherwise ‘dummy’ won’t get set, or will remain as was if previously set.