Printing an upside down triangle in Python 3.4.2?

Question

So, for my programming class I am supposed to write a program that outputs this:

oooooo
ooooo
oooo
ooo
oo
o

I have been able to make it so that the program outputs the triangle right side up but even after looking for help online, I haven't been able to find the solution to turning the triangle upside down. Here is my code:

def main():

base_size = 6

for r in range (base_size):
    for c in range (r + 1):
        print('o', end = '')
    print()

main()

And this is the output I get:

o
oo
ooo
oooo
ooooo
oooooo

Can someone help me out? I am a newbie so this is kind of tough for me even though it's probably pretty simple for you guys.

Thanks in advance!

as a trick, you can use `range`'s `step` argument to step backwards through a range. `range(10, 0, -1)` will give you `10, 9, 8, 7, 6, 5, 4, 3, 2, 1` — Adam Smith, Feb 05 '15 at 21:12
Have a look at the [reversed](https://docs.python.org/2/library/functions.html#reversed) function. — SethMMorton, Feb 05 '15 at 21:12
Hint: The `step` argument to [range](https://docs.python.org/3/library/functions.html#func-range) can be negative. — Two-Bit Alchemist, Feb 05 '15 at 21:13
@SethMMorton -- Congrats for thinking differently than the other commentors -- I actually like your suggestion :-) — mgilson, Feb 05 '15 at 21:13
@DSM a few typos -- apparently I don't know how to use `range`. I got it there eventually! :) — Adam Smith, Feb 05 '15 at 21:14

score 5 · Accepted Answer · answered Feb 05 '15 at 21:16

You're very close. You can use the range function, but step using -1 to walk from n to 0.

You can also make a string by multiplying a character by an integer.

def triangle(n):
    for i in range(n, 0, -1):
        print('o' * i)

Testing

>>> triangle(6)
oooooo
ooooo
oooo
ooo
oo
o

score 0 · Answer 2 · answered Feb 05 '15 at 21:26

Range with a negative step will do the trick (end, ini, step) with step=-1, also you can eliminate one for loop by using lists and join instead:

def trig(base):
   for i in range(base, 0, -1):
       l = ['o']*i
       print(''.join(l))

Edit: @Cyber answer is much better, didn't know you could use "times" operator directly at the string.

Printing an upside down triangle in Python 3.4.2?

2 Answers2