[Tutor] Created Function, Need Argument to be a String
Bryon Adams
bryonadams at openmailbox.org
Mon Dec 12 11:29:20 EST 2016
Is there a way to force my argument to always be a string before
entering the function? Else, is there a better way to go about this? In
whatever program I write, I could change what I want as input to be a
string prior to tossing it into the function but I think it would make
more sense for my function to already do it. The function otherwise
works. This is on Python3.5 under Fedora 25
The only other thing I could think of would be to put exceptions in for
syntax error and whatever else pops up as I go along, though to be
honest it *should* always be a string that gets dumped into the
function. Not sure how I'd put the exception together though since it's
not making it into the function prior to failing.
-------------------------------------------
Error from interpreter: (looks like it's taking issue with it being a
number it doesn't know how to deal with)
>>> ip_checker(169.254.0.1)
File "<stdin>", line 1
ip_checker(169.254.0.1)
^
SyntaxError: invalid syntax
-------------------------------------------
My function:
def ip_checker(ip_address):
'''
Takes one IP address and checks whether it is valid or not.
'''
# Try to convert to integers
try:
ip_addr = [int(i) for i in ip_address.split('.')]
except ValueError:
print('Invalid characters were entered or an octet is empty, please
try again.')
return False
# Determine how many octets were entered
if len(ip_addr) != 4:
print('Incorrect number of octets, please try again.')
return False
# Determine validity of first octet
if ((ip_addr[0] > 223) and (ip_addr[0] < 256)) or (ip_addr[0] == 0):
print('First octet is reserved or zero.')
return False
# Determine if this is a loopback address
if ip_addr[0] == 127:
print('I think that was a loopback address, please try again.')
return False
# Determine if this is an APIPA address
if (ip_addr[0] == 169) and (ip_addr[1] == 254):
print('I think that was an APIPA address, please try again.')
return False
# Determine if the last three octets are between 0-255
for octet in (ip_addr[1], ip_addr[2], ip_addr[3]):
if octet not in [i for i in range(0,256)]:
print('Octet too large or too small, please try again.')
return False
else:
print('The IP address {} is valid.'.format(ip_address))
return True
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