Python loop won't exit on specific user input

Question

Sorry if this is a common question, but every solution I've looked up so far doesn't seem to work.

Basically, I want this loop to exit when the user enters "end" but for some reason it won't actually break the loop.

command = input("Enter command: ") + "\r\n"
while(True):
    print(command)
    if command == "end":
        break
    else:
        tn.write(command.encode("utf-8"))
        ret1 = tn.read_until(b"_DNE", timeout = 10)
        print(ret1)
        command = input("Enter command: ") + "\r\n"

If the user inputs "end" it seems like it ignores the "if" statement and just skips straight to "else"

Have you tried command == "end\r\n" or command == "end\n\r\n"? — muddyfish
– muddyfish, Commented Aug 17, 2015 at 15:45
Why are you appending \r\n to the end of your input string? — ILostMySpoon
– ILostMySpoon, Commented Aug 17, 2015 at 15:56
@ILostMySpoon looks like he's writing to a device that probably uses \r\n as a terminator. That said, I think the best option is probably to define a communicate function that looks like gist.github.com/NotTheEconomist/aa7672106d93bc4079f1 — Adam Smith
– Adam Smith, Commented Aug 17, 2015 at 16:04

Joe Young · Accepted Answer · 2015-08-17 15:51:48Z

2

Instead of trying to attach \r\n to the end of the user input, use raw_input instead

command = raw_input("Enter command: ")
while(True):
    print(command)
    if command.rstrip('\r\n') == "end":
        break
    else:
        tn.write(command.encode("utf-8"))
        ret1 = tn.read_until(b"_DNE", timeout = 10)
        print(ret1)
        command = raw_input("Enter command: ")

edited Aug 17, 2015 at 15:51

answered Aug 17, 2015 at 15:45

Joe Young

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3 Comments

Harpal Over a year ago

If the OP is using python 3 (which I think it is), raw_input() got renamed to input()

Joe Young Over a year ago

@Harpal. Ahh I see. makes sense

Onamar Over a year ago

It worked once I changed your raw_input() back to input(), thanks!

user3917838 · Accepted Answer · 2015-08-17 15:53:13Z

0

Because you add \r\n to your input, whenever you input end, the variable command is holding end\r\n as the string value, not end. So the if statement does not detect it when the user inputs end.

answered Aug 17, 2015 at 15:53

user3917838

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