Make a GCSE student's error work

Question

A GCSE computer science student recently made this hilarious blunder on their exam and posted it online. Now, you must make it work:

day = "Monday"
x = day.length
print(x)

To which they said the output was: 24 hours. Now, we all know that this is incorrect, but to validate this random student, try to golf a program that can take the code above and return the output of 24 hours.

Details

The primary constraint is that the code above must be included, in its entirety, in your program, and it must output the string "24 hours"

This program takes no input, but it must provide its output (to stdout, the screen, or anything) by utilizing a function called print. If this is built in to your language, then use it. If not, then you will need to write your own. A trailing newline may or may not be included, that's up to you.

If your language of choice does not support a variable declaration (or assignment) syntax of the format name = value, then it will not be usable in this challenge. Whichever language you use should support running code of the syntax that is provided in the exam. This eliminates most esolangs, such as Brainfuck, Jelly, and others that don't have = assignment-based variables. Some usable languages could include Swift, Python, Go, and others. The same goes for printing, although as stated earlier, you can create your own print function if that's necessary.

Rules

• The provided code segment must not be in a comment or an unreachable section; it must be executed.
• The provided code segment must be used as-is and cannot be golfed in any way.
• Semicolons (or the equivalent to the end of a line for your chosen language) are the only allowed modification to the provided code segment.

Pseudocode Example

modify class String {
    let length = "24 hours"
}

day = "Monday"
x = day.length
print(x)

This is a Code Golf challenge, so do still try to make the code with the fewest bytes possible!

Answer 1

Python, 68 bytes

class day:length="24 hours";\
day = "Monday"
x = day.length
print(x)

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Not sure the backslash is cheating or not.

Answer 2

R, 60 bytes

day.length="24 hours"
day = "Monday"
x = day.length
print(x)

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. is just a part of variable name in R.

Answer 3

gnuplot, 58 bytes

length="\r24 hours"
day = "Monday"
x = day.length
print(x)

Try it online! (Note that due to a bug, the output from both TIO and gnuplot.io is different from the output produced on a local Windows machine, see the screenshot below.)

How this works:

The dot operator concatenates two strings. This way the string x contains "Monday\r24 hours". When printing x, first "Monday" appears, then the symbol \r (carriage return without linefeed) moves the cursor to the start of the same line and then printing "24 hours" over the string "Monday" overwrites it.

Edit: since this answer has received so many upvotes, I have decided to try and print the string "Monday\r24 hours" from the Linux OS. The result in Python can be checked online here.

Answer 4

Wolfram Language (Mathematica), 65 bytes

print _^:=Print@"24 hours"
day = "Monday"
x = day.length
print(x)

Try it online!

I've taken the liberty of generalizing "This program... must provide its output... by utilizing a function called print" slightly. Strictly speaking, Mathematica doesn't exactly have functions; instead, it has a collection of definitions describing transformations on an expression. During evaluation, these are applied until no more such definitions are applicable.

print _^:=Print@"24 hours"

Add a definition to the symbol print: when it's multiplied with anything, print 24 hours.

day = "Monday"

Assign "Monday" to the symbol day.

x = day.length

Assign the dot product of day and length to the symbol x. There is no built-in rule for evaluating the dot product of a string and a symbol.

print(x)

Multiply print with x.

---

Probably against the spirit of the rules, but line 1 could simply be print:=Print@"24 hours" (-3 bytes): print 24 hours when print is encountered.

Answer 5

JavaScript, 63 bytes

print=_=>alert`24 hours`
day = "Monday"
x = day.length
print(x)

Now using alert rather than console.log, as suggested by Shaggy.

Answer 6

Python, 103 bytes

import gc
gc.get_referents(str.__dict__)[0]["length"]="24 hours"
day = "Monday"
x = day.length
print(x)

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Just for fun - a version with no syntax trickery. Uses implementation-specific behaviour, but works on CPython 3.12.2. str.__dict__ is an immutable proxy but it has a hidden reference to the underlying mutable dictionary, which we can access using the gc module.

Answer 7

Haskell, 91 bytes

main=print"24 hours"where{_._=0;length=0;day = "Monday";
x = day.length;
print(x)=putStr x}

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Thanks to WheatWizard

Answer 8

Uiua, 61 bytes

print=ggg&p
day = "Monday"
x = day.length
print(x)."24 hours"

Try it!

First, let's look at what the given program says in Uiua:

day = "Monday"    # Assign 'day' to the string.
x = day.length    # Assign 'x' to a function which pushes the value
                  # of 'day' and pushes twice the length of an array.
print(x)          # Call a function 'print' after calling the function 'x'.

x has to take an array as input, so we put it on the stack. x has three outputs, all of which are useless, so print has to three values and print "24 hours". We kill two birds with one stone by using "24 hours" as the array x takes. print is defined to pop three stack values and print a string.

If you prefer, the ."24 hours" section can be moved to its own line at the start of the program, but this way is a byte shorter and as far as I can tell is perfectly allowed.

Answer 9

C++ (GCC), 168 135 134 bytes

Thanks to G B for −33 bytes.

#include<cstdio>
#define print(Z)puts("24 hours");}
struct A{A*length;A(char*){}};main(){A*x,
day = "Monday";
x = day.length;
print(x)

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Answer 10

PARI/GP, 58 bytes

a.length="24 hours"
day = "Monday"
x = day.length
print(x)

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PARI/GP's member function syntax is a bit weird. When we define a member function a.length="24 hours", we actually define a new function _.length = (a) -> "24 hours". This function is associated with _.length instead of a, so we can call it from any object, not just a.

Answer 11

Ruby, 68 bytes

def print a;puts"24 hours"end
day = "Monday"
x = day.length
print(x)

Try it online!

For reference, previous solution:

Ruby, 82 bytes

String.class_eval{def length;"24 hours"end}
day = "Monday"
x = day.length
print(x)

Try it online!

Answer 12

VBScript, 263 249 bytes

class o
public length
property let day(x)
end property
property get day
me.length="24 hours"
set day=me
end property
function print(x)
end function
function x
day = "Monday"
x = day.length
print(x)
end function
end class
set x=new o
wscript.echo x.x

day is a date function in VBScript. print is apparently also a function, but I don't know what it does. Wrapping everything in a class allows me to declare local properties to override them, so the only statement that actually achieves anything is x = day.length, which reads the me.length set earlier and returns it as the result of x.x, which we echo at the end of the script.

Answer 13

Perl 5, 85 bytes

sub day:lvalue{$x="24 hours"}sub x:lvalue{$x}
day = "Monday";
x = day.length
print(x)

Try it online!

Explanation

Works by defining two lvalue subroutines which can be assigned to, day and x, with the desired value hardcoded to "24 hours" for day. day.length actually concatenates the output of day and length but since $_ is undefined, length outputs undef which is coerced to the empty string.

Answer 14

PowerShell, 67 bytes

filter print{'24 hours'}
$day = "Monday"
$x = $day.length
print($x)

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This requires a modification to the original code by adding $ in front of the variables; functionally, I don't see any difference to the allowed adding of semicolons at the line ends, or replacing the "=" assignment operator with a different one.

Straightforward: 'filter' is basically the same as 'function' (but with automatic pipeline processing, which is not the point here), but has only 6 instead of 8 characters. It will ignore any arguments and just return the static string '24 hours'.

PowerShell, 167 165 185 171 bytes

165 Found two spaces that could be removed
185 print now generates the output
171 thanks to @julian who golfed the C#

Add-Type 'public class c{static void print(int x){System.Console.Write("24 hours");}public static void d(){int x;var
day = "Monday";
x = day.Length;
print(x);
}}'
[c]::d()

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This takes the original code as C# and compiles it into a class c that can be used by PowerShell. Some further golfing of the C# might be possible ...

Answer 15

Swift, ¹⁰¹ 96 bytes

Assuming I am allowed to answer my own question...

extension String{var length:String{"24 hours"}}
var x="",
day = "Monday"
x = day.length
print(x)

The Swift compiler on tio.run doesn't support Swift v6.0 implicit returning, but a different one does. Try it here.

Answer 16

Raku (Perl 6) (rakudo), 126 124 bytes

use MONKEY-TYPING;augment class Str {method length {"24 hours"}};my \day:=my \x:=$;
day = "Monday";
x = day.length;
print(x)

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Answer 17

Google Sheets, 77 bytes

=let(print,lambda(_,"24 hours"),_,
day = "Monday"&
x = day.length,
print(x)
)

Answer 18

Lua, ⁸⁴ 65 bytes

day={length="24 hours"}os.
day = "Monday"
x = day.length
print(x)

Try it online!

-19 thanks to Daniel Schepler

Answer 19

Haskell, 270 bytes

{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedRecordDot #-}
{-# LANGUAGE DataKinds #-}
#define print(x) in putStrLn x
import GHC.Records
instance GHC.Records.HasField "length" String String where getField=const"24 hours"
main=let 
 day = "Monday"
 x = day.length
 print(x)

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Answer 20

Fortran (GFortran) -cpp, 102 bytes

#define print(x)print*,"24 hours"
#define x !
#define day !
day = "Monday"
x = day.length
print(x)
end

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Zsh attempt failed - Fortran works though! The -cpp flag allows me to #define away the problematic code. print(x) is a (poorly named) macro that prints the text in a way the compiler understands. The assignments for x = and day = just become comments (!).

Answer 21

Progress Openedge ABL, 198 bytes

def var day as char.
def var x as char.
def temp-table day
FIELD length as char init "24 Hours".
function print char(x as char):
message x.
end.
create day.
day = "Monday".
x = day.length.
print(x).

Works by defining each component of the code. First instance of day is read as a normal variable. day.length is read as the field 'length' in the table 'day'.

Try It
You may need to switch the dojo to run on v12.2.12 to avoid an error with the site

Answer 22

Lua, 62 bytes

print=print("24 hours")
day = "Monday"
x = day.length
print(x)

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Answer 23

Rust, 145 bytes

macro_rules!x{($a:stmt;$b:tt=$c:expr;$e:stmt)=>{$a;$b=();print!("24 hours")}}fn main(){let(day,x);x!{
day = "Monday";
x = day.length;
print(x)
}}

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the macro x! rewrites the code to:

day = "Monday";
x = ();
print!("24 hours")

Answer 24

Japt, 47 bytes

$day = "Monday"
x = day.length
print(x)$`24 ÊÀs

Test it

Answer 25

Rexx (Regina), 63 bytes

Here are two solutions in Rexx. Thanks to its flexible syntax the solutions are quite compact.

Since Rexx does not have print function/statement, it is defined in both cases within the program.

In the first and shorter solution (below) the user-defined print function takes no argument (x is ignored), prints the hardcoded string 24 hours and stops the execution. No need to care about return statement, which is normally required. Although print is formally a function, the way it is defined it could only run once, which is enough for the task.

day = "Monday"
x = day.length
print(x)
print:say"24 hours"
exit

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Rexx (Regina), 71 bytes

This longer solution is actually more exciting. This time the print function prints the content of the global variable x. The content of x comes from day., which is a separate from day variable. My guess is that since length is not defined it is simply ignored and, so, day.length evaluates to day..

day.="24 hours"
day = "Monday"
x = day.length
print(x)
print:say x
exit

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Answer 26

Java 22, 210 159 bytes

Modified after @noodle person comment

class C{String day,length="24 hours";void print(String s){System.out.print(s);}void main(){String x;C day=new C();day.
day = "Monday";
x = day.length;
print(x);
}}

Un-golfed

class C {
  String day, length = "24 hours";
  void print(String s) { System.out.print(s); }
  void main() {
    String x;
    C day = new C();
    day.
    day = "Monday";
    x = day.length;
    print(x);
  }
}

Must be compiled and run with --release 22 and --enable-preview

javac --release 22 --enable-preview C.java
java --enable-preview C

Answer 27

C (MSVC), 118 bytes

#define day /##/
#define x /##/
#define print(x)puts("24 hours");}
int main() {
day = "Monday"
x = day.length
print(x)

Try in GodBolt