title: how to keep special characters in df column names in R?
body: <p>I'm processing hundreds of MS excel sheets with R (and gdata), in order to save their data in a database.  Unfortunately some (actually a lot) column names contain signs like "+", "-", and others, which are then replaced by "." (dots) in the data frame column names I get.<br>
  My question is : how can I keep these signs ? </p>
  
  <p>(I need them to match these names afterward with another source.)</p>
  
  <p>Thanks for helping.</p>