Funny(deadly) Interview Question

[Siddhesh Deodhar]

For my campus placements, Interviewer asked me one funny(deadly) question.
He said, "write a program whose output is the program itself".

I thought on it for while, Interviewer was smiling saying take your own time kid and started smoking.

After stretching my head i shouted, "Sir, within my code I will read the same code file and display"
"Amazing kid"..you are right, please write it and show me.
With victorious face, i wrote code in front of him in C considering standard's, indentation and other conventions.

Interviewer was very happy and started behaving like he is my uncle. . Asked me few questions about my family and some other technical stuff.
I got selected without any hassle.

He gave me few sample answers which my friends told him. Following are some which i rememebred
- We need to read RAM
- We need to print code as it is in "print" statements.

Well, This might be a joke, but the question he asked me can stand deadly when you are under pressure.

[Ryan McGuire]

However often the executable (or the .class or .jar file for Java) is distributed without the source code file. If you had to solve the problem WITHOUT the source code available at run time, how would you do it.

[Tina Smith]

Another take on this problem is something like...

public class Test
{
    public static void main( String[] args )
    {
        Process pr = Runtime.getRuntime().exec( "java " + args[0] );
        pr.waitFor();
    }
}

and run the program with the following arguments:
java Test Test

[Ernest Friedman-Hill]

There is a word for such a program; it's called a "Quine", if you're interested in Googling. The solution you've described -- reading the source and printing it -- is considered a cheat, and is not a valid quine. It's entirely possible to create genuine quines that don't read their own source.

[Yogesh Gnanapraksam]

Tina Smith wrote:Another take on this problem is something like...

public class Test
{
    public static void main( String[] args )
    {
        Process pr = Runtime.getRuntime().exec( "java " + args[0] );
        pr.waitFor();
    }
}

and run the program with the following arguments:
java Test Test

I don't understand !!! how this is supposed to be Quine

[fred rosenberger]

Tina Smith wrote:Another take on this problem is something like...

public class Test
{
    public static void main( String[] args )
    {
        Process pr = Runtime.getRuntime().exec( "java " + args[0] );
        pr.waitFor();
    }
}

and run the program with the following arguments:
java Test Test

This won't compile.

[Matthew Brown]

Ernest Friedman-Hill wrote:The solution you've described -- reading the source and printing it -- is considered a cheat, and is not a valid quine.

It's probably the sort of cheat that would go down well in an interview if you can't actually create a genuine quine, though .

[Mike Simmons]

Matthew Brown wrote:

Ernest Friedman-Hill wrote:The solution you've described -- reading the source and printing it -- is considered a cheat, and is not a valid quine.

It's probably the sort of cheat that would go down well in an interview if you can't actually create a genuine quine, though .

Also a perfectly legitimate answer if the interviewer hasn't actually specified that you can't read the source file. Might as well go with a solution that's simple and easy to maintain.

[Daniel Doboseru]

@Siddhesh: you said:

For my campus placements, Interviewer asked me one funny(deadly) question.

What do you mean be campus placements? You're student and for a place in the campus you had a technical interview as for hiring?

[Yogesh Gnanapraksam]

What do you mean be campus placements?

It refers to an event organized by the college management in which various companies visit the college campus and conduct written tests and technical interviews and give a job offer to the candidates who seem to fit their requirements.

[Daniel Doboseru]

Oh, i see. Very nice thing. We have such a thing too: several companies come and present their offer, technologies etc and afterwards accept CVs from interested students, offering them the chance of a interview. We call them generically InfoTechs (ElectroTech, InstallTech, MechaniTech depending of the faculty).

[simi selva]

nice.. I have to learn more about quines...

[Randall Twede]

from wikipedia:

A quine is a computer program which takes no input and produces a copy of its own source code as its only output. The standard terms for these programs in the computability theory and computer science literature are self-replicating programs, self-reproducing programs, and self-copying programs.

sounds a lot like a worm to me.

where did this interview take place?
viruses are us ?

[Randall Twede]

However often the executable (or the .class or .jar file for Java) is distributed without the source code file. If you had to solve the problem WITHOUT the source code available at run time, how would you do it.

so much for my career as a virus writer

[Bhanuprakash Sreenivas]

Since Java is compiled and then interpreted , technically it is not feasible to get a exact copy of the
source code.
For example - The comments of a source will not be visible.

Directly interpreted languages like Javascript can be used to achieve this.

[Ernest Friedman-Hill]

Bhanuprakash Sreenivas wrote:Since Java is compiled and then interpreted , technically it is not feasible to get a exact copy of the
source code.
For example - The comments of a source will not be visible.

Directly interpreted languages like Javascript can be used to achieve this.

Indeed, the many working examples above are all imaginary.

[Bhanuprakash Sreenivas]

Ernest Friedman-Hill wrote:

Bhanuprakash Sreenivas wrote:Since Java is compiled and then interpreted , technically it is not feasible to get a exact copy of the
source code.
For example - The comments of a source will not be visible.

Directly interpreted languages like Javascript can be used to achieve this.

Indeed, the many working examples above are all imaginary.

Oops.. jumped the gun

[naveen yadav]

here is java Quine program

import java.io.*;
public class Quine{

public static void main(String... arg){

try{
FileInputStream ob = new FileInputStream("Quine.java");

int i =0;
while((i=ob.read())!=-1)
{
char ch = (char)i;
System.out.print(ch);
}
}
catch(IOException exp){
exp.printStackTrace();
}
}
}

[fred rosenberger]

naveen yadav wrote:here is java Quine program

import java.io.*;
public class Quine{

public static void main(String... arg){

try{
FileInputStream ob = new FileInputStream("Quine.java");

int i =0;
while((i=ob.read())!=-1)
{
char ch = (char)i;
System.out.print(ch);
}
}
catch(IOException exp){
exp.printStackTrace();
}
}
}

This doesn't work...I get a "File not found" error...Note that there are examples above that DO work, without requiring the source file.

[Andy Jack]

an important question is - why do i need a quine ?

[Matthew Brown]

You don't. There's no practical use (that I can think of), it's just a puzzle. Some people find the challenge interesting.