Happy numbers: Difference between revisions

=={{header|CLU}}==

<lang clu>sum_dig_sq = proc (n: int) returns (int)

sum_sq: int := 0

while n > 0 do

sum_sq := sum_sq + (n // 10) ** 2

n := n / 10

end

return (sum_sq)

end sum_dig_sq

is_happy = proc (n: int) returns (bool)

nn: int := sum_dig_sq(n)

while nn ~= n cand nn ~= 1 do

n := sum_dig_sq(n)

nn := sum_dig_sq(sum_dig_sq(nn))

end

return (nn = 1)

end is_happy

happy_numbers = iter (start, num: int) yields (int)

n: int := start

while num > 0 do

if is_happy(n) then

yield (n)

num := num-1

end

n := n+1

end

end happy_numbers

start_up = proc ()

po: stream := stream$primary_output()

for i: int in happy_numbers(1, 8) do

stream$putl(po, int$unparse(i))

end

end start_up </lang>

{{out}}

<pre>1

7

10

13

19

23

28

31</pre>