I'm sorry but this is so insanely wrong. If they did that, the difference between the measurement they give you and the actual length would be massive. I measured my 183 cm Line Chronics and the running length was right around 150 cm.
To the OP: for whatever reason K2 skis are always a bit longer than what they say. The 179 cm Domain will probably actually be 181-182 cm. However, since they're rockered they feel a bit shorter while skiing. You'll be fine with the 179 cm length.