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Loops & Iterators

Inclusive and Exclusive Ranges

You saw a bit of new syntax in the previous exercise: for num in 1...10. What this says to Ruby is: "For the variable num in the range 1 to 10, do the following." The following was to puts "#{num}", so as num took on the values of 1 to 9, one at a time, those values were printed to the console.

The reason this program counted to 9 and not 10 was that we used three dots in the range; this tells Ruby to exclude the final number in the count: for num in 1...10 means "go up to but don't include 10." If we use two dots, this tells Ruby to include the highest number in the range.

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