How to use for in Ruby?

The syntax of for in Ruby is:

for «variável» in «lista»
    «comandos»
end

To make a loop from 0 to 9 (10 reps), something equivalent to for(i=0; i<10; i++) , you will do:

for i in 0..9
    puts "o valor de 'i' é #{x}"
end

And if you want, you can use a variable to indicate the boundary of your loop:

n=9
for i in 0..n
    puts "o valor de 'i' é #{x}"
end

If you do not want to include the last value, use ... instead of .. . In this case you will get the same result using 0..9 or 0...10 .

Rubistas are not fans of explicit ties like for and while .

It is very common to see loops using iterators, as does Array#each :

a = [ "a", "b", "c" ]
a.each {|x| print x, " -- " }
=> a -- b -- c --

Or even using Integer#times :

5.times do |i|
  print i, " "
end
#=> 0 1 2 3 4

Of course, each or times does not always solve your problem, but it's rare that I had to use for or while in Ruby.