What is the point of having "x...n" in Ruby?

Question

I'm just curious.

Arent both of the code snippets below doing the same thing? Why would someone want to use ... instead of .., wouldnt .. be easier to read?

for x in 1...11
     puts x
end

for x in 1..10
 puts x
end

Sorry if this is too subjective, I just dont understand why I would want to go from 1 to (n-1) instead of 1 to n

Answer 1

10.5 is included in 1...11, but not in 1..10.

It's not 1 to n vs. 1 to (n - 1), it's 1 <= x <= n vs. 1 <= x < m.

Answer 2

Sometimes the index in some data structure goes form 0 to struct.size() - 1. It's helpful then to have a way of saying this:

a = ['a','b','c']
for i in 0 ... a.length
   puts a[i]
end

will print 'a', 'b', 'c'. It you use the .. form it will print an additional nil.