How to guess the 4 digit secret code entered by user(unknown to us)?

Question

can someone explain how to do this in python? the idea is to figure out the 4 digit code(ex: 3968) entered by the user. how would one design an algorithm to go about finding this? here is what i got..:

code=int(input("Enter 4 digit secret code:"))
count=0000
while(count!=code):
    count=count+1
print("Your code was",count)

this works perfectly....Except when the code starts with 0... Ex: 0387 it prints " Your code was 387" as appose to 0387

whats a quick fix for this?

This question actually was asked previously, see http://stackoverflow.com/q/134934/1165330 for answeres. — Jonathan, Nov 04 '12 at 20:51
Also, you should never, ever, store anything as an int (or float) unless you intend to do arithmetic with it. This is a perfect example why this is so. Phone numbers, post codes etc. are not numbers, they are strings and should be treated as such. — Tim Pietzcker, Nov 04 '12 at 20:53
@LennartRegebro: But the algorithm can't be changed to cope with an alphabetic code like `ABCD` as a result. — Eric, Nov 04 '12 at 20:58
@LennartRegebro: OK, but the entire example is quite contrived. — Tim Pietzcker, Nov 04 '12 at 20:59

Lennart Regebro · Accepted Answer · 2012-11-04T20:58:09.593

5

print("Your code was %04i" % count)

The % means that here comes a variable. The 04 means zero-pad it to four characters. The i means it's an integer. Docs here.

Alternative version, using the new, more flexible .format() formatting:

print("Your code was {:04n}".format(count))

edited Nov 04 '12 at 20:58

answered Nov 04 '12 at 20:49

Lennart Regebro

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Martijn Pieters · Answer 2 · 2012-11-04T20:59:13.900

3

You need to print it with some formatting:

print("Your code was {0:04d}".format(count))

which will zero-pad your number up to 4 digits. See the string formatting documentation for more details.

Alternatively, you can use the str.zfill() method to add the extra zeros after string conversion:

print("Your code was", str(count).zfill(4))

edited Nov 04 '12 at 20:59

answered Nov 04 '12 at 20:51

Martijn Pieters

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Hah! I beat you with two minutes! :-) – Lennart Regebro Nov 04 '12 at 20:54
@LennartRegebro: but without documentation! I hesitated if I should add an answer, but since yours was so very basic and lacking any explanation, I did so anyway. :-P – Martijn Pieters Nov 04 '12 at 20:55
Right, I should add doc links. I did add the format formatting for completeness even though I don't like it. :) – Lennart Regebro Nov 04 '12 at 20:56
@LennartRegebro: I am coming round to it; it *is* more flexible, and supports mixing positional and keyword parameters. – Martijn Pieters Nov 04 '12 at 20:57
**Too** flexible. I had some horror show example somewhere. It's very easy to obfuscate. – Lennart Regebro Nov 04 '12 at 20:59

Eric · Answer 3 · 2012-11-04T21:39:55.687

1

Here's a way of doing it purely using strings:

import itertools

code = input("Enter 4 digit secret code:")

for attempt in itertools.product("0123456789", repeat=4):
    attempt = ''.join(attempt)
    if attempt == code:
        print("Your code was", attempt)
        break

edited Nov 04 '12 at 21:39

answered Nov 04 '12 at 20:55

Eric

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Nope! "count" should be "attempt" in print statement other then that it works although the printed result is a comma separated list.. to fix this i just did this: if j == code: print("Your code was",j) break it now prints it as one string no spaces or commas :D – 3MIN3M Nov 04 '12 at 21:11

How to guess the 4 digit secret code entered by user(unknown to us)?

3 Answers3