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Programming Ruby 3.2 (5th Edition): B4.0 page 521, my world has collapsed . .

BernardK

BernardK

Programming Ruby 3.2 (5th Edition): B4.0 page 521, my world has collapsed . .

@noelrappin

… when I read that in “abcdefg”, f is the character at index -1, the last character :astonished:.

page 521, first bullet. The problem is that the explanation starts with an inclusive range, “abcdefg”[1..3], then switches to excluding ranges. I suggest to use inclusive ranges :

  • so “abcdefg”[3..-2] returns “def”, since d is the character at index 3, and f is the character at index -2

  • Halfway ranges also work, so “abcdefg”[..-2] (or “abcdefg”[...-1]) returns all but the last character

  • and “abcdefg”[3..] returns everything from index 3 on (“abcdefg”[3...] including the last character could be seen as an anomaly)

4 comments
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First Post!

noelrappin

noelrappin

Author of Modern Front-End Development for Rails

Wow, not sure how I missed that. I think inclusive ranges are easier to understand here.

Changed to

"abcdefg"[4..-1] returns "efg", since e is the character at index f, and f is the character at index -1, the last character. Halfway ranges also work, so "abcdefg"[..-2] returns all but the last character, and "abcdefg"[3..] returns everything from index 3 on

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