How to detect 'bad' characters in expressions in the notebook?

*To*: mathgroup at smc.vnet.net*Subject*: [mg113346] How to detect 'bad' characters in expressions in the notebook?*From*: "Nasser M. Abbasi" <nma at 12000.org>*Date*: Sun, 24 Oct 2010 06:07:00 -0400 (EDT)*Reply-to*: nma at 12000.org

Experts; I copied a Mathematica expression from a PDF file to a Mathematica notebook (by using the mouse, selected the expressions and pasted it into a new cell in the notebook). The expression looked fine, nothing that I can see wrong with it. But when I execute it, Mathematica complained with an error message that did not make any sense given what I have on the screen. I knew that there was some problem with the copy, because when I typed the same exact command below it, it worked with no errors. But looking at the screen, both what I copied and what I typed, are exactly the same. Absolutely exactly the same expressions looked the same on the screen as you can see yourself by looking at the screen shot, link below. But when I converted the commands to inputForm to compare the copied command with the I typed, I saw the difference. In the PDF copied command, it had PlotRange->{} The arrow was the problem. For some reason, it remained of some encoding which did not match Mathematica's own -> that one enters by typing dash followed by > which then Mathematica converts automatically to a nice solid one glyph ->. Here is an image showing the problem http://12000.org/tmp/hidden_stuff/image.png And here is the notebook http://12000.org/tmp/hidden_stuff/hidden.nb So, my question: was there a way I could have asked Mathematica to highlight such characters as being ones which it did not recognize? This would have saved much time. I have had such problems before, where what I look at in the notebook, is not what I think it is. The above is an example. I guess my lesson for today: next time I copy something from a PDF file or other source to the notebook, I better examine each character in inputForm before using it even if it did look OK on the screen. Sounds like so much fun. --Nasser