Not getting correct values for string variable in python

Question

I have below code that I have written

class Test:
    def __init__(self,value):
        ''' Constructor. '''
        self.ext_ip_address = value
    def ip_address_changed(self):
        with open(IP_ADDR, 'r') as ip_address:
            ip_addr = ip_address.read().replace('\n','')
            if not ip_address == self.ext_ip_address:
                self.ext_ip_address = ip_address
                print 'IP ADDR', ip_addr
                print 'EXT IP ADDR', self.ext_ip_address
                return True
        return False



# Run following code when the program starts
if __name__ == '__main__':
   test_obj = Test('')
   if test_obj.ip_address_changed():
      print "IP changed"
   else:
      print "IP constant"

Here I am reading the IP address of a machine from file (i.e. ip_addr local variable), then I am checking whether the IP address of machine is changed from the last value (i.e. self.ext_ip_address). Then I am trying to print the values of both variables ip_addr and self.ext_ip_address. For ip_addr, I am getting the proper value. But for self.ext_ip_address I am getting strange value as below:

IP ADDR 192.168.44.100
EXT IP ADDR <open file '/usr/local/bin/data/ip_address.dat', mode 'r' at 0xb772e230>

Please let me know what is the reason for this. Thanks in advance!!!

You should use ip_address.read().strip() in instance of ip_address.read().replace('\n','') to avoid trailing whitespaces messing with your values — VMRuiz
– VMRuiz, Commented May 19, 2017 at 7:20
@VMRuiz Thanks for the tip, but my comment was not meant as an answer. I was responding to a comment Kuro has posted, but apparently has deleted. — Chris
– Chris, Commented May 19, 2017 at 7:22

Arya McCarthy · Accepted Answer · 2017-05-19 07:20:32Z

4

You mixed up ip_addr and ip_address in two places. ip_address is your file, which is what you wound up printing instead of the address you had in mind.

class Test:
    def __init__(self,value):
        ''' Constructor. '''
        self.ext_ip_address = value
    def ip_address_changed(self):
        with open(IP_ADDR, 'r') as ip_address:
            ip_addr = ip_address.read().strip()  # Per VMRuiz's comment
            if not ip_addr == self.ext_ip_address:  # HERE
                self.ext_ip_address = ip_addr  # AND HERE
                print 'IP ADDR', ip_addr
                print 'EXT IP ADDR', self.ext_ip_address
                return True
        return False

Clearer variable names will prevent this problem in the future.

edited May 19, 2017 at 7:20

answered May 19, 2017 at 7:17

Arya McCarthy

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