[Tutor] NEWBIE- how to make a program continue

[Andy W]

> I am very NEW to programing. Here is my question. I have written a small
program( with the help of teaching python in 24 hours) I added the year =
input line it works well except i want it to countue doing what it does
utill i tell it to stop. How do I do this?
>
> below is the script i am using
>
> def julian_leap (y) :
>     if (y%4) == 0:
>         return 1
>     return 0
> year = input ( " Type in a year:" )
> if julian_leap (year):
>     print year, "is leap"
> else:
>     print year, "is not a leap year"
>
>
> Tahnks for ant help offered,
> Robert

Hi Robert,

Seeing as you're new, I'll try to be a little more clear and thorough than I
usually am. No promises though!

To repeat the instructions, you require a loop statement. Using a "while"
statement would be most appropriate I think.
The basics go as follows:

while <test clause>:
    statement 1
    ...
    statement n

as long as the <test clause> evaluates to true, the loop will continue. Each
time it will go through to the end, unless told otherwise. To "tell it
otherwise", and make it exit the loop at a certain time, we use the "break"
statement. So

while 1:
    break

will exit the loop straight away. To return to the top of the loop, we can
use another statement called "continue".

while 1:
    continue
    break

That one will continue forever. Don't try it out, because it'll make your
interpreter hang ;)

So there's a few ways we can approach your problem. I'll just look at the
part that needs to be in the loop.
BTW, this isn't tested. I've made one error already tonight, I hope I don't
get myself crucified.

The two most obvious options to me are
1) Use an "always true" loop (ie. while 1:) , and use "break" to get out of
it.
2) Use a variable as the test clause, and set it to exit the loop.

1st way:

while 1:
    year = input ( " Type in a year:" )
    if julian_leap (year):
        print year, "is leap"
    else:
        print year, "is not a leap year"
    keep_going=raw_input("Do you want to keep going, yes or no?")
    if keep_going=="no":
        break

2nd way:

done=0

while not done:
    year = input ( " Type in a year:" )
    if julian_leap (year):
        print year, "is leap"
    else:
        print year, "is not a leap year"
    keep_going=raw_input("Do you want to keep going, yes or no?")
    if keep_going=="no":
        done=1

HTH
Andy

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