Loop until a specific user input [duplicate]

Question

I am trying to write a number guessing program as follows:

def oracle(): n = ' ' print 'Start number = 50' guess = 50 #Sets 50 as a starting number n = raw_input("\n\nTrue, False or Correct?: ") while True: if n == 'True': guess = guess + int(guess/5) print print 'What about',guess, '?' break elif n == 'False': guess = guess - int(guess/5) print print 'What about',guess, '?' break elif n == 'Correct': print 'Success!, your number is approximately equal to:', guess oracle()

What I am trying to do now is get this sequence of if/ elif/ else commands to loop until the user enters 'Correct', i.e. when the number stated by the program is approximately equal to the users number, however if I do not know the users number I cannot think how I could implement and if statement, and my attempts to use 'while' also do not work.

Fred Foo · Accepted Answer · 2011-11-13 20:24:17Z

19

As an alternative to @Mark Byers' approach, you can use while True:

guess = 50 # this should be outside the loop, I think while True: # infinite loop n = raw_input("\n\nTrue, False or Correct?: ") if n == "Correct": break # stops the loop elif n == "True": # etc.

edited Nov 13, 2011 at 20:24

answered Nov 13, 2011 at 20:16

Fred Foo

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5 Comments

Mark Byers Over a year ago

+1 similar to my update. I think the use of input here is also wrong.

Fred Foo Over a year ago

@MarkByers: changed it to raw_input. From the looks of the print statements, the OP is using Python 2.

George Burrows Over a year ago

Could either of you tell me why the code now terminates after entering True or False?

Mark Byers Over a year ago

Err... perhaps because you put a break statement there?! What exactly did you think would happen when it hit the break statement? Perhaps you should read a Python tutorial...

George Burrows Over a year ago

Sorry I'm being stupid, I have been up for too long haha, thanks for the help :)

Mark Byers · Accepted Answer · 2011-11-13 20:18:43Z

Your code won't work because you haven't assigned anything to n before you first use it. Try this:

def oracle(): n = None while n != 'Correct': # etc...

A more readable approach is to move the test until later and use a break:

def oracle(): guess = 50 while True: print 'Current number = {0}'.format(guess) n = raw_input("lower, higher or stop?: ") if n == 'stop': break # etc...

Also input in Python 2.x reads a line of input and then evaluates it. You want to use raw_input.

Note: In Python 3.x, raw_input has been renamed to input and the old input method no longer exists.

+1, though it would be more pythonic to use None to denote "no value".
Could either of you tell me why the code now terminates after entering True or False?

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