Factors of an integer: Difference between revisions

=={{header|Crystal}}==

{{trans|Ruby}}

<lang ruby>struct Int

def factors() (1..self).select { |n| (self % n).zero? } end

end</lang>

As we only have to loop up to <math>\sqrt{n}</math>, we can write

<lang ruby>struct Int

def factors

f = [] of Int32

1.upto(Math.sqrt(self)).select { |i| (self % i).zero? }

.each { |i|

f << (self // i) unless i == (self // i)

f << i

}

f.sort

end

end</lang>

'''Tests:'''

<lang ruby>

[45, 53, 64].each {|n| puts "#{n} : #{n.factors}"}</lang>

{{out}}

<pre>

45 : [1, 3, 5, 9, 15, 45]

53 : [1, 53]

64 : [1, 2, 4, 8, 16, 32, 64]</pre>