You've made some very good points. I now think it would have been best to only offer s/^0$/1/--even though the OP said "Word boundaries work !", evidencing that s/\b0\b/1/ met his/her needs.

I'm not sure about your array elements. Cells don't contain the 007, 0.03 or 0.0 that you placed into an array (unless, of course, it's text, but the OP seems to suggest that s/he's dealing with numeric values). Those elements are the formatting results of the numeric values 7, .03 and 0, respectively.