When, if ever, is “number of lines of code” a useful metric?

Question

Some people claim that code\'s worst enemy is its size, and I tend to agree. Yet every day you keep hearing things like

• I write blah lines of code in a day.

Answer 1

It's a terrible metric, but as other people have noted, it gives you a (very) rough idea of the overall complexity of a system. If you're comparing two projects, A and B, and A is 10,000 lines of code, and B is 20,000, that doesn't tell you much - project B could be excessively verbose, or A could be super-compressed.

On the other hand, if one project is 10,000 lines of code, and the other is 1,000,000 lines, the second project is significantly more complex, in general.

The problems with this metric come in when it's used to evaluate productivity or level of contribution to some project. If programmer "X" writes 2x the number of lines as programmer 'Y", he might or might not be contributing more - maybe "Y" is working on a harder problem...