Comment Why not just declare all variables as strings? (Score 1) 1067
A few years back I made a pretty important report that listed percentages. At the time it didn't seem to matter what happened when data was missing, so I created a function that would take a numerator and denominator and spit out 0 if the denominator was 0. (This was in SSRS, so I couldn't use IF since it processes every part of the function regardless of the boolean outcome.) Looking back, while this hasn't caused any problems that I'm aware of, I regret the decision. Displaying -- is actually more informative than 0%, because it tells the user that the data is not available, not that it's 0%, which can be misleading.
Some day I'll fix it when I have time (and am not browsing Slashdot), but my word of warning to you is: don't.