on writing a while loop for rolling two dice

[Terry Reedy]

On 8/28/2021 8:00 AM, Hope Rouselle wrote:
> How should I write this?  I'd like to roll two six-sided dice until I
> get the same number on both.  I'd like to get the number of times I
> tried.  Here's a primitive I'm using:
> 
> --8<---------------cut here---------------start------------->8---
>>>> x, y = roll()
>>>> x
> 6
>>>> y
> 6 # lucky
> 
>>>> x, y = roll()
>>>> x
> 4
>>>> y
> 1 # unlucky
> --8<---------------cut here---------------end--------------->8---
> 
> Here's my solution:
> 
> --8<---------------cut here---------------start------------->8---
> def how_many_times():
>    x, y = 0, 1
>    c = 0
>    while x != y:
>      c = c + 1
>      x, y = roll()
>    return c, (x, y)
> --8<---------------cut here---------------end--------------->8---
> 
> Why am I unhappy?  I'm wish I could confine x, y to the while loop.  The
> introduction of ``x, y = 0, 1'' must feel like a trick to a novice.  How
> would you write this?  Thank you!

Something like (untested)

c = 0
while True:
     c += 1
     x, y = roll()
     if x == y:
         return c, (x,y)

or even better to me, as it will not loop forever if you mess up the 
condition

for i in range(1, 1000000):
     x, y = roll()
     if x == y:
         return i, (x,y)
# return "The universe ends as the essentially impossible happened"


-- 
Terry Jan Reedy