Some Self Duplicating Code

Computer Science Level 2

Take a look at the python code below. Which segment of code should be replaced in place of the first line( $\color{#D61F06} {\text{???????????}}$ ) so that the when the code runs, it prints exactly itself ?

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???????????
print "x =", x
for i in x: print i

x = ['print "x =", x', 'for i in x: print i'] x = ['print "x =', x", 'for i in x: print i'] x = ['print x=x','for i in x:print i'] x = "['print "x =", x', 'for i in x: print i']"

1 solution

Thaddeus Abiy
Apr 18, 2014

The answer is

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x = ['print "x =", x', 'for i in x: print i']
print "x =", x
for i in x: print i

Pieces of code that do this are called Quines. Take a look at the wikipedia page for more.

Also in the 'see also' section of the page there is another interesting page on Tupper's self-referential formula

$Tupper$ Tupper

which graphs itself when plotted

tupp tupp

I suck at proggraming any good websites to learn computer science

Mardokay Mosazghi - 7 years, 1 month ago

Hey I know some cool sites which may help you :

http://www.codecademy.com/learn { best and the most user friendly site : recommended } http://www.cppforschool.com/
http://www.learnjavaonline.org/
http://www.javabeginner.com/

Sushant Samuel - 7 years, 1 month ago

You can try thenewboston on youtube if you are a visual guy,but I am not a fan of videos. Personally I learnt python here back when I was your age.Once you learn a few of the basics,just do problems ,try projecteuler most of the problems are really hard but you will learn a lot.

I am assuming you do not know how to program.

Thaddeus Abiy - 7 years, 1 month ago

There is also : http://codecombat.com

A very fun way to learn.

Vitor da Silva - 7 years, 1 month ago

one word -quine

Daniel Lim - 7 years, 1 month ago

Some Self Duplicating Code

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