[Question]
  [
*This is the robbers' thread. The cops' thread is [here](https://codegolf.stackexchange.com/q/135363/58826).*
Your challenge is to crack a cop's submission by finding an input that makes it halt. You don't have to find out why, or all inputs that make it halt if there's more than one, or the input the cop intended, just one input will do.
Once you have cracked a submission, post a link to it in a comment or edit to the cop's post. You can also flag your submission for a mod to edit it in the cop's post. Also, post the input used and a link to the cop's post in an answer in this thread. The robber that cracks the most submissions wins.
**Multiple people can post cracks to the same cop submission, as long as they are different.**
(If SE converted your duplicate answer to a comment, you may want to vote on [this feature request](https://codegolf.meta.stackexchange.com/q/13437/58826))
---
# Looking for uncracked submissions?
```
fetch("https://api.stackexchange.com/2.2/questions/135363/answers?order=desc&sort=activity&site=codegolf&filter=!.Fjs-H6J36vlFcdkRGfButLhYEngU&key=kAc8QIHB*IqJDUFcjEF1KA((&pagesize=100").then(x=>x.json()).then(data=>{var res = data.items.filter(i=>!i.body_markdown.toLowerCase().includes("cracked")).map(x=>{const matched = /^ ?##? ?(?:(?:(?:\[|<a href ?= ?".*?">)([^\]]+)(?:\]|<\/a>)(?:[\(\[][a-z0-9/:\.]+[\]\)])?)|([^, ]+)).*[^\d](\d+) ?\[?(?:(?:byte|block|codel)s?)(?:\](?:\(.+\))?)? ?(?:\(?(?!no[nt][ -]competing)\)?)?/gim.exec(x.body_markdown);if(!matched){return;}return {link: x.link, lang: matched[1] || matched[2], owner: x.owner}}).filter(Boolean).forEach(ans=>{var tr = document.createElement("tr");var add = (lang, link)=>{var td = document.createElement("td");var a = document.createElement("a");a.innerText = lang;a.href = link;td.appendChild(a);tr.appendChild(td);};add(ans.lang, ans.link);add(ans.owner.display_name, ans.owner.link);document.querySelector("tbody").appendChild(tr);});});
```
```
<html><body><h1>Uncracked Submissions</h1><table><thead><tr><th>Language</th><th>Author</th></tr></thead><tbody></tbody></table></body></html>
```
  
[Answer]
# [Malbolge, Doorknob](https://codegolf.stackexchange.com/a/135583/72703)
[Try it online](https://tio.run/##S0oszvifnFiiYKeQkZhTopebmKNgY6Ogrqf@X8NWrchKOd@2Lsckq8o83bSspCSpqKAgLi8nJyorIyOMKy0lJSgpwd/aSkPdKzJCOSysLiu4OjDHLsvX29vS0z2Zyy3RJT4iNiY6KjIiPKzYz8zHxCsmOjvSNSPMKTU4OSmRSzXeNza2zjPS3di1ssLUxNhIG2iBbp52jmaWeoaqk8F/PS6uzOT8vDIF3RKFzOJ8XQsLU0tdQ4UaBf38ghJ9oGOT8nPSU@EMuB/@u8Uf3mJoZGxiamZuYWkAAA) (Thanks [Dennis](https://codegolf.stackexchange.com/users/12012/dennis)!)
Input for Windows: `F_⌠1234567890`
Input on Linux based system using ISO-8559-1: `F_ô1234567890`
The heart of how the Malbolge program worked is that it depended on a behavior of the Malbolge interpreter which causes an infinite loop if it encounters any instruction which is not between 33 and 126. The program was constructed such that your input would allow you to modify a single instruction.
I modified the interpreter to dump the program memory state at the beginning of execution and to also produce 'normalized' source code which takes the form of a list of [op codes](http://www.lscheffer.com/malbolge_spec.html) that will be run during the execution of the program. With that information you could (slowly) determine that even though the program took 
 13 inputs only the 1st and 3rd inputs actually mattered.
Looking through the normalized code and memory dump (and a touch of debugger help) I devised the following:
> 
> a = op(input 1, 29524)
> 
> 
> b = op(input 3, a)
> 
> 
> c = op(486, b)
> 
> 
> d = op(c, 37)
> 
> 
> e = d/4 + d%3 \* 3^9
> 
> 
> e must be between 33 and 126
> 
> 
> 
Where `op` is the so called tritwise "op" that is described in the specification. Using this information you can write a simple program which iterates over the possible inputs (0 to 255) and finds all solutions which meet the above criteria. I had found 2219 possible solutions, some of which will probably not be working solutions (you can't input the required characters). Specifically the above inputs are based on the solution: 
`(Input 1 = 70, Input 3 = 244)`
[Answer]
# [JavaScript (in Browser)](https://codegolf.stackexchange.com/a/135551/61875)
```
document.all
```
This is falsy, surprisingly
Edit: [why is `document.all` falsy](https://stackoverflow.com/questions/10350142/why-is-document-all-falsy)?
[Answer]
# JS (ES6), [Juan Tonina](https://codegolf.stackexchange.com/a/135385/65836)
```
+0,-0
```
Took a bit of looking in `Object.is` to find. Basically, `+0 === -0` since `===` checks them as numbers, and `0` is finite, but `Object.is` sees `+0` and `-0` as different objects. Very smart cop :)
[Try it online!](https://tio.run/##y0osSyxOLsosKNHNy09J/Z9m@1@jQqdS09auujwjMydVo0LR1raypsY/KSs1uUQvsxgoq1CpWVOjmFnslpmXWQJUgcKr1NS0rv2fpqFtoKNroPkfAA "JavaScript (Node.js) – Try It Online")
[Answer]
# [Python, Siphor](https://codegolf.stackexchange.com/a/135490/10894)
```
class A:
    i = True
    def __eq__(self, a):
        self.i = not self.i
        return self.i
a = A()
f(a)
```
We just redefine equality to behave exactly as required to get the program to terminate.
[Answer]
# [Braingolf](https://codegolf.stackexchange.com/a/135367/58826)
```
-1
```
Any number less than `0` works. 
[Try it Online!](https://tio.run/##SypKzMxLz89J@/8/2lA79v///7qmAA)
[Answer]
# [PHP, Sisyphus](https://codegolf.stackexchange.com/a/135550)
`(-0[0)> deal with it=1` 
The parse\_str function changes the spaces and other characters to underscores. If you put a [ used for Array delimiter without closing, it changes it to an underscore but has the effect of not translating the following spaces (I don't know why).
[Try it online!](https://tio.run/##K8go@P/fxr4go4CrILGoODW@uKRIQyWxKL0s2jBWRyVe05qrPCMzJ1VDUSU@Wl1D1yDeQNNOISU1MUehPLMkQyGzRD1W0/r///9AqWh0KVtDAA "PHP – Try It Online")
[Answer]
# JavaScript (Node.js), [Adnan](https://codegolf.stackexchange.com/a/135408)
`[]` and `[]` seem to work. I tried a bunch of them including `null`, `undefined`, `NaN`...
`[] >= [] && [] <= [] && [] != []` evaluates to true.
Moral of the story: JavaScript is *weird*.
[Try it online!](https://tio.run/##y0osSyxOLsosKNHNy09J/Z9m@7/C1q7S1q66PCMzJ1VDUaPCzrZSTa3CBkwq2lZqalrX/k/TiI7VBOH/AA "JavaScript (Node.js) – Try It Online")
[Answer]
# JavaScript (ES7), [Arnauld](https://codegolf.stackexchange.com/a/135398/71612)
## Standard
`"8e7"` is solution
```
var crack_me = (x=0)=>{for(;~x/x.length**3!=-2962963;);}
var key = "8e7"
crack_me(key)
console.log("stopped :)")
```
## Hack
No need to calculate this number, we can redefine `length` property
This sets `~x/x.length**3!=-2962963` to `false`
```
var crack_me = (x=0)=>{for(;~x/x.length**3!=-2962963;);}
var key = {toString:()=>"2962962",length:"1"}
crack_me(key)
console.log("stopped :)")
```
## [Operators priority](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Operators/Operator_Precedence)
`~` [bitwise not](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators#Bitwise_NOT) is first
`** exponentiation` second
`/ division` third
[Answer]
# [Bash, Veedrac](https://codegolf.stackexchange.com/a/135630/48931)
```
LD_TRACE_LOADED_OBJECTS
```
[Try it online!](https://tio.run/##S0oszvj/P7WiIL@oREFJxVDJNiM1p4BLPykzT78ytfj///8@LvEhQY7OrvE@/o4uri7x/k5ers4hwQA "Bash – Try It Online")
From the `ld.so(8)` manpage:
> 
> **LD\_TRACE\_LOADED\_OBJECTS**
> 
> 
> If set (to any value), causes the program to list its dynamic
>  dependencies, as if run by `ldd(1)`, instead of running
>  normally.
> 
> 
> 
[Answer]
## Mathematica, [JungHwan Min](https://codegolf.stackexchange.com/a/135505/8478)
```
Unevaluated@Throw@"hammertime"
```
No clue whether this is the intended solution, but it passes in an expression that doesn't get evaluated until it's referenced as `#` inside the function, which will cause it turn return from the function immediately without doing any further evaluation. You can see that the function is actually called (instead of just throwing the exception before even invoking the function) by changing the function to:
```
#0[Print@"stop";#;$IterationLimit=∞]&
```
Which will indeed print the `stop` before throwing the error.
[Answer]
# R, [Jarko Dubbeldam](https://codegolf.stackexchange.com/a/135857/53286)
```
function(x)if(is.list(x))return(1)
```
First time contributing anything, so do call out any mistakes I've made in format.
Pretty sure this is valid. Just a rewrapping of is.list(), right?
[Answer]
# [Retina](https://github.com/m-ender/retina), [PunPun1000](https://codegolf.stackexchange.com/a/135382/41805)
```
11111
```
[Try it online!](https://tio.run/##K0otycxL/P8/jsuQSzshzlDDUFuTS8Xw0DYVNa7iBA17G9u4mkPbNEHCGva2IJa9op7WoW0xhtoqmlxch7YB@RBmHEgNSEKFC2iSIZeh4f//hiAAAA "Retina – Try It Online")
Any input with *n* `1`s where the sum of the divisors of *n+1* is equal to *n+1* should work.
[Answer]
# Node.js, [Adnan](https://codegolf.stackexchange.com/a/135408/58826)
`{}` and `{}` or any 2 objects are the two inputs. I don't even understand how this works.
Here's JS's amazing object compare logics:
```
console.log({} == {});
console.log({} === {});
console.log({} > {});
console.log({} < {});
console.log(!!{});
console.log({} >= {});
console.log({} <= {});
```
[Answer]
# [Ruby](https://codegolf.stackexchange.com/a/135465/65905)
```
exit
```
without newline. `3.send('exit')` surely isn't equal to `5`, but it executes [`Kernel#exit`](https://ruby-doc.org/core-2.4.1/Kernel.html#method-i-exit):
> 
> Initiates the termination of the Ruby script by raising the SystemExit
>  exception
> 
> 
> 
It's possible to call `exit` on `3` [because](https://ruby-doc.org/core-2.4.1/Kernel.html):
> 
> The Kernel module is included by class Object, so its methods are
>  available in every Ruby object [as private methods].
> 
> 
> 
[`abort`](https://ruby-doc.org/core-2.4.1/Kernel.html#method-i-abort) also works:
> 
> Terminate execution immediately, effectively by calling
>  Kernel.exit(false). If msg is given, it is written to STDERR prior to
>  terminating.
> 
> 
> 
[Answer]
# [JavaScript (Node.js)](https://nodejs.org), [programmer5000](https://codegolf.stackexchange.com/a/135513/65836)
Already cracked, but mine is slightly different :) Don't have enough rep to comment over in the cops. Also feel free to edit to fix formatting, my first post here.
Mainly I set `__proto__` equal to a function that throws. Taken from looking at the Mozilla page for proto. (Sorry, low rep, can't post a link.)
```
x = {}
let No = function () { throw 'halted' }
x.__proto__ = new No()
```
```
f = x=>{while(x.__proto__);}
```
[Try it online!](https://tio.run/##TYvBDYQgEAD/VrE/4aENXLgSbIEQXQIXwhpchYRQO/K830wy8zOPufbkT14iHdgLKKhtCsiw0WB7x509RRASKrBLlGF2JjAeM7SprFqfiZi0HnHEPC4hux1S1Ldm5wOKv0h@WreiyP4C "JavaScript (Node.js) – Try It Online")
EDIT: Got some rep, so here's the link: [Mozilla `__proto__`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/proto)
[Answer]
# [Bash, Sisyphus](https://codegolf.stackexchange.com/a/135595/12012)
```
kill 0
```
Fortunately, `kill` is a shell builtin.
[Try it online!](https://tio.run/##S0oszvj/P7lAQT8pM0@/JLFIQY8rNa9MQTdTIcAxxMNWJSDcRcHTVsUeoiAJqFxBt0hBN1lBScVQias8IzMnVcHKOiUfTOSl/v//PzszJ0fBAAA "Bash – Try It Online")
[Answer]
# Javascript, [programmer5000](https://codegolf.stackexchange.com/a/135468)
## Max string length
Uses a string with a length one less than what your engine supports. When adding `"h"` to this string, an error is thrown. [Try it online!](https://tio.run/##bZCxbsQgDIb3PoWVieiUUzsjTmrndup4uoFQJ6GiEIGTpjrl2VNIuIsqdQCL3/b/2XzKUQbldU9VLWs0lXUfuBgkaMQkTtfvThtk06HoipLPSzNYRdpZaJGezZcL9CanV7Tv5FkJ1weAUXroPY4vMmAAAecLz2odlSgUskgK@Z@1HmBDkB@wzArsDsd@CB1LrSXPudXnINa4aXO8Z1CSVMeSSXo3zgNLWB2Zu51B21JXPXHQJ/HIoar0jbpPtDPujWd9yayNA3dQOh5p8DZPNC83p4b9901xkT8msVA5G5zBo3EtS4vOyy8)
```
function getAlmostMaxLenStr() {
  var prevBases = [];
  var base = "a";
  try {
    while(true) {
      prevBases.push(base);
      base += base;
    }
  } catch(e) {}
  for (var i = prevBases.length-1; i>=0; --i) {
    try {
      base += prevBases[i];
    } catch (e) {}
  }
  return base;
}
f(getAlmostMaxLenStr());
```
## Cross-origin block
Heavily inspired by [the answer from @jadkik94](https://codegolf.stackexchange.com/a/135874/72685), but works everywhere. Creates a cross-origin iframe, then passes the `.contentWindow` of said iframe. This fails when the function tries to use the value due to cross-origin safety.
```
let f=x=>{
  try {
    console.log(x+"h"); // we don't want to lock up your browser, do we ;)
  } catch (e) { console.log("Halted!\n",e); }
}
let iframe=document.createElement("iframe");
const url = location.host.indexOf("google") === -1 ? "https://google.com" : "https://stackexchange.com";
iframe.src=url;
iframe.onload=a=>f(iframe.contentWindow);
document.body.appendChild(iframe);
```
## Primitive value
Variant of the `.toString()` answers - this just uses `toPrimitive` instead. It returns an object as the primitive value, which Javascript doesn't know how to handle (so it throws an error). [Try it online!](https://tio.run/##HYtLDoMgEED3nGLiCtLoBQw9Q5Mumy6AjgWDToNTqyGc3RK37zOa1SwuhQ@31liM7UwvPCIyDHrT1/zzIaLcLo1vVF9OQXYEDVkAPO77ZCl2TLcUpsBhxadUOSF/0wy5FFH6g9N@xoOso@pFAWfYeZCoTu5oXihiF@ldUfXHHw)
```
f({
  [Symbol.toPrimitive](){return {}}
});
```
[Answer]
# [JavaScript (Babel Node)](https://babeljs.io/), [Conor O'Brien](https://codegolf.stackexchange.com/a/135523/72664)
(Repost, accidentally put in cops.) Not sure what was intended but positive decimals that aren't enormous all seem to work.
Also I guess I still can't comment in Cops.
```
f(0.1)
console.log('done')
```
[Try it online!](https://tio.run/##TdlNbl3HEYDReVaReCJyYOF19T8UesCdUPZTooARBVlxEMTZhBamLSk2@xSTybMAgR8sqc59t6v/9vDLw88/fnr/8fP3bx/eXh@///D00/Xbu7v7ux/@ff3l4fHmu/fvbj7/6@P16d0f7/909@rDP/7@9vrp1e393eXN/37n65f/@62vX377ve9ef7p@vD58vmm3@au4vX3zz7@@f7ze3P/57vLrr/d3d@X5M54/6/Nne/7sz5/j@XM@f67nz31@yg@fny7nx8v5@XIC5RTKSZTTKCdSTiVOJfw/nEqcSpxKnEqcSpxKnEqcSj2VeirVH@VU6qnUU6mnUk@lnko9lXYq7VTaqTR/I6fSTqWdSjuVdirtVPqp9FPpp9JPpfuLPZV@Kv1U@qn0UxmnMk5lnMo4lXEqw7/PqYxTGacyTmWeyjyVeSrzVOapzFOZ/plPZZ7KPJV1KutU1qmsU1mnsk5lncoyLaeyTmWfyj6VfSr7VPap7FPZp7JPZRu6nDpjdzF3F4N3MXkXo3cxexfDdzF9F@N30XsZY70c5JzkHOWc5RzmnOYcZ/NcDHSJdKFnpouhLqa6GOtirovBLia7GO1itktNaHrGu5jvYsCLCS9GvJjxYsiLKS/GvLSUq2fSi1EvZr0Y9mLai3Ev5r0Y@GLiS89HgZ6hL6a@GPti7ovBLya/GP1i9ovhLyOfLXrmvwBQCCgIFAYKBIWCgkHhoMx8WOmhUFgoMBQaCg6FhwJEIaIgUVY@/fSoKFgULgoYhYyCRmGjwFHoKDsfp/k89UDlI/gIPoKP4CP4CD6Cj@AjSj6g9fgIPoKP4CP4CD6Cj8jnfT7wX574evnMz4d@PvXzsZ/P/Xzw8xF8BB9R8ytEj4/gI/gIPoKP4CP4CD6Cj2j5naTHR/ARfAQfwUfwEXwEH8FH9PyS0@Mj@Ag@go/gI/gIPoKP4CNGfmvq8RF8BB/BR/ARfAQfwUfwETO/hvX4CD6Cj@Aj@Ag@go/gI/iIld/renwEH8FH8BF8BB/BR/ARfMTOF4V8U/CqwEflo/JR@ah8VD4qH5WPykct@eqhx0flo/JR@ah8VD4qH5WPykeNfJfR46PyUfmofFQ@Kh8134zy1SjfjV5ejvTy9Sjfj/IFKd@Q8hWJj8pH5aPyUVu@benxUfmofFQ@Kh@Vj8pH5aPyUXu@vunxUfmofFQ@Kh@Vj8pH5aPyUUe@D@rxUfmofFQ@Kh@Vj8pH5aPyUWe@YOrxUfmofFQ@Kh@Vj8pH5aPyUVe@serxUfmofFQ@Kh@Vj8pH5aPyUXe@Auc7sJdgPhofjY/GR@Oj8dH4aHw0PlrJl2o9PhofjY/GR@Oj8dH4aHw0PlrkW7oeH42Pxkfjo/HR@Gh8ND4aH63ma78eH42Pxkfjo/HR8gyRh4g8ReQx4uUcoZcniTxK5FkiDxN8ND4aH42PxkfreTDR46Px0fhofDQ@Gh@Nj8ZH46ONPOno8dH4aHw0PhofjY/GR@Oj8dFmHp30@Gh8ND4aH42Pxkfjo/HR@Ggrz2J6fDQ@Gh@Nj8ZH46Px0fhofLSdh7s83Tne8dH56Hx0PjofnY/OR@ej89FLHhf1@Oh8dD46H52Pzkfno/PR@eiR5089PjofnY/OR@ej89H56Hx0PnrNA60eH52Pzkfno/PR@eh8dD46H73lCVmPj85H56Pz0fO0ncftPG/ngTtP3C9Hbr08dOepO4/dfHQ@Oh@dj85H56P/7uPrl99/IQhIB6QD0gHpgHRAOiAdkA5In7kV0AOkA9IB6YB0QDogHZAOSAekr1wz6AHSAemAdEA6IB2QDkgHpAPSd@4tcnFhcwHIAGQAMgAZgAxABiADkAHIKLkJ0QNkADIAGYAMQAYgA5AByABkRK5W9AAZgAxABiADkAHIAGQAMgAZNXc1eoAMQAYgA5AByABkADIAGYCMlssfPUAGIAOQAcgAZAAyABmADEBGz22SHiADkAHIyMVUbqZyNZW7qVxO5XbqZT2llwuq3FDxMfgYfAw@Bh@Dj8HHmLnv0uNj8DH4GHwMPgYfg4/Bx@BjrFyg6fEx@Bh8DD4GH4OPwcfgY/Axdm7kciVnJ8fH5GPyMfmYfEw@Jh@Tj8nHLLnj0@Nj8jH5mHxMPiYfk4/Jx@RjRi4N9fiYfEw@Jh@Tj8nH5GPyMfmYNbeQenxMPiYfk4/Jx@Rj8jH5mHzMlmtNPT4mH5OPycfkY/Ix@Zh8TD5mzz2pHh@Tj8nH5GPyMfmYfEw@Jh9z5OJVj4/Jx8wVbu5wc4mbW9xc4@YeNxe5L5tcvdzl8jH5mHxMPiYfk4/Jx@RjrlwN6/Ex@Zh8TD4mH5OPycfkY/Ixd@6ac9ls28zH4mPxsfhYfCw@Fh@Lj8XHKrm91uNj8bH4WHwsPhYfi4/Fx@JjRa7D9fhYfCw@Fh@Lj8XH4mPxsfhYNffrenwsPhYfi4/Fx@Jj8bH4WHyslgt7PT4WH4uPxcfiY/Gx@Fh8LD5WzxsAPT4WH4uPxcfiY/Gx@Fh8LD7WyCsFPT4WH4uPxcfiY/Gx@Fh8LD7WzDsKPT5WXnbkbUded@R9R1545I1HXnnkncfLpYceH4uPxcfiY/Gx@Fh8LD4WH2vnLUpeo7hH4WPzsfnYfGw@Nh@bj83H5mOXvJfR42PzsfnYfGw@Nh@bj83H5mNHXvTo8bH52HxsPjYfm4/Nx@Zj87Fr3hzp8bH52HxsPjYfm4/Nx@Zj87FbXkXp8bH52HxsPjYfm4/Nx@Zj87F73m3p8bH52HxsPjYfm4/Nx@Zj87FHXpbp8bH52HxsPjYfm4/Nx@Zj87Fn3r7p8bH52HxsPjYfm4/Nx@Zj87FXXufp5bVg3gvmxWDeDObVYN4N5uVg3g7m9eCzjx9@@@@@ffOfb@9uLq/L7R9@fPrw89Pj9fXj019uXv309OH66vbbt/8C "JavaScript (Babel Node) – Try It Online")
[Answer]
## [Javascript (NOT node.js)](https://codegolf.stackexchange.com/a/135468/9365), programmer5000
This can't be added because it creates an object that has no toString because a new `Set` does not inherent prototypes from from `Object`.
input:
```
new Set()
```
[Try it online!](https://tio.run/##y0osSyxOLsosKNEtLshMSS3Kzc/LTq38/7/CNi@1XCE4tURD05qrwtauujwjMydVo0JbKUNJ07r2/38A "JavaScript (SpiderMonkey) – Try It Online")
[Answer]
# Bash 4.2, [Dennis](https://codegolf.stackexchange.com/a/135590/21194)
```
PATH=1
```
Clearly not the intended solution, because it works on newer bash as well.
[Try it online.](https://tio.run/##S0oszvj/Pye1REHFkKsytfj///8BjiEetoYA)
[Answer]
# [Octave](https://www.gnu.org/software/octave/), [Stewie Griffin](https://codegolf.stackexchange.com/a/135415/20268)
Input:
`exit`
Reasoning:
`input` evalutes whatever is input. `exit` exits the program.
[Try it online!](https://tio.run/##y08uSSxL/f@/wjYzr6C0RENdXdO6PCMzJ1XBsKZCJzUv5f//1IrMEgA "Octave – Try It Online")
[Answer]
# Python 2, [Foon](https://codegolf.stackexchange.com/a/135525/21194)
```
__import__("os")._exit(0)
```
What it says on the tin, basically.
[Try it online.](https://tio.run/##K6gsycjPM/r/vzwjMydVwdCKS6GkqBJIKlQo2Cpk5hWUlmhocimkViSnFpSAhAsSi4v//4@Pz8wtyC8qiY/XUMovVtLUi0@tyCzRMNAEAA)
[Answer]
## Python 3 (CPython), [Veedrac](https://codegolf.stackexchange.com/a/135565/967)
```
a=('',(type,),{})
X=type(*a)(*a)
X.__class__=X
```
[Try it online!](https://tio.run/##HYuxCsMgFEX39xU2S94rUgrdBKf@QgY3EWOJNCSiD6qUfrttOtzhcM5NjZd9u/U@h4eYsErW3FIgBeK1xDUIxkqxCBZ7/vmDSF3BaRxHiUcqSb4/BOb/w7OjY2Au1vrVlWKtNsC5qQkNQag@JFYpx41xuGfnn2E@DdT7Fw "Python 3 – Try It Online")
[Answer]
# Python 3, [Siphor](https://codegolf.stackexchange.com/a/135606)
This was fun. We need to make the `type(x) != str` check pass, so we need to control the return value of `type()`. We have to override the `__class__` attribute and replace it with a custom object, that extends `type`, which has the `__ne__` method replaced by one that always returns false. This makes it pass the type check, but the search will fail because `o` is not a str.
```
class m(type):
    def __ne__(a,b):
        return False
class c:pass
o=c()
o.__class__=m("",(c,),{})
f(o)
```
[Answer]
# R, [Jarko Dubbeldam](https://codegolf.stackexchange.com/a/135742/21194)
Just an invalid regex.
```
"["
```
[Try it online.](https://tio.run/##K/r/P802rTQvuSQzP0@jQrM8IzMnVcNQMzNNIyc1L70kAyimmV6UWqBRoaOursmVpqEUraT5/z8A)
[Answer]
# [Python, Siphor](https://codegolf.stackexchange.com/a/135606/10894)
```
f('t=False')
```
Crashes due to an `UnboundLocalError`.
I think this is hapening because my `t=False` overrides the higher-scoped `t` with the local `t`, but it's not set at the time of the loop, causing the crash.
[TIO](https://tio.run/##bY0/C8IwEMX3fIozS1IIXdwKnfwDLjq5uYR4oYXWhOTAFvGzx8vkoMPB@73HexdXGsJjW8odPXi9NJ0A6qWUlUlX/Cp4DuOEQF20OTO@3kLUSPBxRcA4x5AIErLk0hqRF2HTQ6YEIXHQZrTJDTrJW5ZmMexcz6fdZX/484DS2lHvwhzZ1dT6kGZLPGnUrIzCBZ1qBODiMNJvveaamuK1ov5op4yqKR8)
[Answer]
# Commodore 64 Basic, [Mark](https://codegolf.stackexchange.com/a/135554/21194)
If I understood this correctly (and it's entirely plausible I have not), you just need to overflow the floating point variable.
```
9999999999999999999999999999999999999999999999999999999999999999.9
```
[Answer]
# Bash 4.2, [Dennis](https://codegolf.stackexchange.com/a/135658/21194)
```
-9223372036854775808/-1
```
Why though, Dennis? y u do dis?
[Answer]
# C#, [TheLethalCoder](https://codegolf.stackexchange.com/a/135696/15738)
```
System.Nullable`1[[System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]
```
Or any other nullable class.
[Answer]
# C#, [TheLethalCoder](https://codegolf.stackexchange.com/a/135834)
```
new char[0]
```
`string.Empty` (`""`) is always interned. Therefore, an empty array or `null` will work.
]