Implementing Loops from Pseudocode

Question

I was wondering if anyone could suggest to me how to implement this loop in the following pseudocode:

8: loop
9: while f[0] = 0 do
10: for i = 1 to N do
11: f[i ¡ 1] = f[i]
12: c[N + 1 - i] = c[N - i]
13: end for
14: f[N] = 0
15: c[0] = 0
16: k = k + 1
17: end while
18: if deg(f) = 0 then
19: goto Step 32
20: end if
......... ...... ....
31: end loop

My question is how I should implement the loop that starts on line 8 and ends on 31; I am comfortable with the statements between lines 8 to 31, but what kind of loop do I use on line 8, and what conditions do I give for the loop?

Thanks in advance.

What language? That looks like an infinite loop to me, you can use whatever loop construct you want. Just make sure you have a way to do step 19. — Carl Norum
– Carl Norum, Commented Feb 23, 2010 at 2:07
I'm using Java, @jldupont, well it's for my university project, so yes homework in a way :-) — ms87
– ms87, Commented Feb 23, 2010 at 2:19
@Neville: then may I suggest you add the relevant homework tag next time? — jldupont
– jldupont, Commented Feb 23, 2010 at 2:25

John Kugelman · Accepted Answer · 2010-02-23 02:16:04Z

2

That's an infinite loop. No conditions, just loop forever. The only way out is to get to step 19. In C-like languages you can write that as while (true) or for (;;):

for (;;) {
    // ...

    if (deg(f) == 0) {
        goto afterLoop;
    }

    // ...
}

afterLoop:
// ...

goto is frowned upon, though. It'd be better to replace goto Step 32 with a break statement, which exits a loop immediately:

for (;;) {
    // ...

    if (deg(f) == 0) {
        break;
    }

    // ...
}

For what it's worth, if you didn't have steps 21-30 you could use a do/while loop, where the loop condition goes at the bottom of the loop instead of the top:

do {
    // ...
}
while (deg(f) != 0);

That would work if lines 18-20 were the final lines in the loop. Since they're not, it looks like option #2 is the one to go with.

edited Feb 23, 2010 at 2:16

answered Feb 23, 2010 at 2:09

John Kugelman

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1 Comment

ms87 Over a year ago

Thanks a lot, i had no idea it's an infinite loop, I knew I had to break out of it, i think I'll just implement it with an infinite for loop. Thanks again.

anon · Accepted Answer · 2010-02-23 10:28:16Z

1

If you are going to write pseudocode in such detail, you might as well write in the target language. Pseudocode should be a much broader brush - something like this (not related to your code):

for each bank account
   check balance as of last month
   if balance greater than promotion limit
      send out valued customer pack
   endif
endfor

answered Feb 23, 2010 at 10:28

anon

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