Microsoft Office Tutorials and References
In Depth Information
4.6 Debugging
Precisely because Excel cannot warn us about logical errors, they are the most dangerous, because
we think that everything is correct.
4.6 Debugging
Invariably, you will encounter errors in your code. Design-time and compile-time errors are
relatively easy to deal with because Excel helps us out with error messages and by indicating the
offending code. Logical errors are much more difficult to detect and to fix. This is where
debugging plays a major role. The Excel IDE provides some very powerful ways to find bugs.
Debugging can be quite involved, and we could include a whole chapter on the subject. There are
even special software applications designed to assist in complex debugging tasks. However, for
most purposes, a few simple techniques are sufficient. In particular, Excel makes it easy to trace
through our programs, executing one line at a time, watching the effect of each line as it is
Let us try a very simple example, which you should follow along on your PC. If possible, you
should arrange your screen as in Figure 4-8 . This will make it easier to follow the effects of the
code, since you won't need to switch back and forth between the Excel window and the Excel
VBA window. The code that we will trace is shown in Example 4-1 . Note that lines beginning
with an apostrophe are comments that are ignored by Excel.
Figure 4-8. Top-and-bottom windows for easy debugging
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