Convert string with comma to integer
You may also want to make sure that your code localizes correctly, or make sure the users are used to the "international" notation. For example, "1,112" actually means different numbers across different countries. In Germany it means the number a little over one, instead of one thousand and something.
Corresponding Wikipedia article is at http://en.wikipedia.org/wiki/Decimal_mark. It seems to be poorly written at this time though. For example as a Chinese I'm not sure where does these description about thousand separator in China come from.
Some more convenient
"1,1200.00".gsub(/[^0-9]/,'') it makes "1 200 200" work properly aswell