Is it a substring of itself?

Question

Given a string, return whether the string is a substring of the program's source code.

Standard quine rules apply, meaning you cannot read your own source code. The length of the input is guaranteed to be less than or equal to the length of the program. You may return any two distinct values, not necessarily truthy and falsey values. You may also submit a function, rather than a full program.

This is a code-golf so shortest code wins!

An example

If your source code is print(input() = False), it should return True for nt(i but False for tupn.

Answer 1

Python 2, 41 bytes

s="print input()in's=%r;exec s'%s";exec s

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Answer 2

JavaScript, 25 bytes

f=s=>('f='+f).includes(s)

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I'm personally not a fan of this, but it's allowed.

Alternate (invalid?) solution, 19 bytes

This takes input as a regex.

f=s=>s.test('f='+f)

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Answer 3

Java 8, 124 112 bytes (function)

p->{String s="p->{String s=%c%s%1$c;return s.format(s,34,s).contains(p);}";return s.format(s,34,s).contains(p);}

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Here is it as full program instead (to see one of the reasons why functions are allowed on PPCG, because some languages -like Java- require very verbose mandatory boilerplate code for full programs).

Java 8, 226 214 bytes (full program)

interface M{static void main(String[]a){String s="interface M{static void main(String[]a){String s=%c%s%1$c;System.out.print(s.format(s,34,s).contains(a[0]));}}";System.out.print(s.format(s,34,s).contains(a[0]));}}

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Explanation:

• The String s contains the unformatted source code.
• %s is used to input this String into itself with the s.format(...).
• %c, %1$c and the 34 are used to format the double-quotes.
• s.format(s,34,s) puts it all together.

And then .contains(...) is used to check if this source code contains the given input.

Answer 4

Bash, 43, 28 bytes

[[ $BASH_COMMAND = *"$1"* ]]

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Answer 5

QBIC, 28 bytes

?instr(B+B,;)#?instr(B+B,;)#

This prints 0 if the input is not a substring of the source, and X otherwise where X is the (first) index of the substring.

Explanation

Latter part:
#?instr(B+B,;)#   Define a string literal B$ with a copy of the source

First part:
?                 PRINT
 instr(   , )     the index of
           ;          the cmd line parameter A$
       B+B            in B$ concatenated with itself

# defines a string literal in QBIC, and assigns it to the first available string variable. That is B$ in this program, because A$ is already taken by ; (read a string from cmd line). Then, everything up to the delimiter is fed into the literal; the delimiter is a backtick - which also makes it the only ASCII char not includable in string lits. In this case, QBIC doesn't need a backtick, because the literal is terminated at the end of the code by QBIC's auto-close feature. For more information on QBIC's literals, see the Showcase thread.

Answer 6

Haskell, 92 bytes

import Data.List;f s=isInfixOf s$(++)<*>show$"import Data.List;f s=isInfixOf s$(++)<*>show$"

Try it online! Obvious extension of the standard quine. Getting rid of the import would be nice, but I doubt isInfixOf can be computed in a shorter amount of bytes.

Answer 7

Wolfram Language (Mathematica), 33 bytes

!StringFreeQ[ToString[#0], #1] & 

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Answer 8

Jelly, 10 bytes

“;⁾vṾƓẇ”vṾ

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How it works

“;⁾vṾƓẇ”vṾ  Main link. No arguments.

“;⁾vṾƓẇ”    Set the left argument and the return value to ';⁾vṾƓẇ'.
         Ṿ  Uneval; yield '“;⁾vṾƓẇ”'.
        v   Dyadic eval; eval ';⁾vṾƓẇ' with argument '“;⁾vṾƓẇ”'.

  ⁾vṾ       Yield 'vṾ'.
 ;          Append it to '“;⁾vṾƓẇ”', yielding the source code.
     Ɠ      Read a string from STDIN.
      ẇ     Check if it's a substring of the source code.

Answer 9

Julia, 72 bytes

I now understand what people mean when they say that quine problems are just variations on the classic quine.

x="~y=contains\"x=\$(repr(x));\$x\",y)";~y=contains("x=$(repr(x));$x",y)

Explanation

#Defines x to be the next line of the source, with the help of escaping characters
x="~y=contains\"x=\$(repr(x));\$x\",y)"; 
#Interpolates together a comparison string, including repr(x), the re-escaped from of x, and x itself, for comparison. 
~y=contains("x=$(repr(x));$x",y)

Answer 10

Perl 5, 60 + 2 (-pl) bytes

$_=(sprintf$a=q($_=(sprintf$a=q(%s),$a)=~/\Q$_/),$a)=~/\Q$_/

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Answer 11

05AB1E, 17 bytes

0"D34çýIå"D34çýIå

Modification of the default quine 0"D34çý"D34çý by adding Iå.

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Explanation:

0                    # Push 0 to the stack
                     #  STACK: [0]
 "D34çýIå"           # Push the string 'D34çýIå' to the stack
                     #  STACK: [0, 'D34çýIå']
          D          # Duplicate this string
                     #  STACK: [0, 'D34çýIå', 'D34çýIå']
           34ç       # Push '"' to the stack
                     #  STACK: [0, 'D34çýIå', 'D34çýIå', '"']
              ý      # Join the stack by this '"' delimiter
                     #  STACK: ['0"D34çýIå"D34çýIå']
               I     # Take the input
                     #  STACK: ['0"D34çýIå"D34çýIå', 'Iå"D']
                å    # Check if it's a substring of the source code
                     #  STACK [1]
                     # (Output the top of the stack implicitly)