Question

I’m trying to write a script that accepts input for a number, and then checks to see

(a) that the input is in fact a number, and
(b) that the number in question is less than or equal to 17.

I’ve tried a variety of “if” statements to no avail, and now I’m trying to wrap my head around “try” statements. This is my best attempt to date:

def listlength():
    print "How many things (up to 17) do you want in the list?"
    global listlong
    listlong = raw_input("> ")
    try:
        listlong = int(listlong)
        listlong <= 17
    except:
        print "Gotta be a number less than 17, chumpy!"
        listlength()
    liststretcher()

It works for the first element in the try: if it’s not a numeral, I have to run through the listlength function again. But the second element (<=17) is completely ignored.

I’ve also tried

try:
    listlong = int(listlong) and listlong <= 17

…but that still gives me only a functional first check, and ignores the second entirely.

I also get the same result if I have two try statements:

    try:
        listlong = int(listlong)
    except:
        print "Gotta be a number, chumpy!"
        listlength()
    try: 
        listlong <=17
    except: 
        print "Gotta be less than 17!"
        listlength()
    liststretcher() 

Is there a way to have try: check two things, and require both to pass before moving past the exception? Or do I have to make two different try: statements in the same definition before moving on to the liststretcher() command?

In response to S.Lott, below: my intention was that “try: listlong <=17” would check to see if the “listlong” variable was shorter than or equal to 17; if that check failed, it would then move to the “except”; if it passed, it would move on to liststretcher() below.

Reading the answers to date, I’ve got about eight things to follow up on…

Answer 1

You have most of the answer:

def isIntLessThanSeventeen(listlong):
    try:
        listlong = int(listlong) # throws exception if not an int
        if listlong >= 17:
            raise ValueError
        return True
    except:
        return False

print isIntLessThanSeventeen(16) # True
print isIntLessThanSeventeen("abc") # False