Printable View
Hello,
I know 1 way of making a program which prints its own source code! And that is, first i save the source code and open that file only and print it :)
But i dont want that. What i want is without saving the source code it should print its own source code! Is it possible?and if yes then how?please tell me??
Not possible. Source code is not stored in the compiled executable.
You might be able to do it with some kind of pseudo-macro, but that would be compiler dependent (and ugly).
Why would you want to do it anyways?
Im kind of a noob but would it not be possible to store the code using File I\O and then print it
Yes, it is possible. Search the web for quine.Quote:
What i want is without saving the source code it should print its own source code! Is it possible?and if yes then how?please tell me??
Fun, laughter, peace and joy.Quote:
Why would you want to do it anyways?
hahahahahueheh laserlight! Yes why would anybody want to do it?you're right!
But this is an interview question. When we go for interview we can't ask the interviewer this question! like why would you want to do it?for fun?peace?laughter and joy?can we??
http://www.techinterviews.com/?p=317
If someone asked such a stupid question during an interview, first I'd ask them why they'd want to do that, then I'd wonder if it's the right place for me to work.Quote:
Originally Posted by chottachatri
The question is not so stupid. Everyone with the "classical" programming education is aware of such program. So if the person learns about it during interview it can indicate possible "shortcuts" in his education curve... And this can be futher investigated with other questionsQuote:
If someone asked such a stupid question during an interview
vart! yeah it's a classical programming question. Hey please tell me how to do it?is it possible or not?since the source code that we are making is residing in memory only i believe there has to be a way out. If we can know at which memory location the source code is currently running we can assign it's address to some character pointer variable..it's just a guess please if you know then tell me
i know 1 method as i said but that's a simple file reading and printing on console. But i dont want that the source code should be on hard disk...it should be in memory only and be displayed on console..
Eh, I told you to search for quine, apparently you did, and you even posted a link to a page that has a solution. What more do you want?
but laserlight what does this mean??
Code:char*f="char*f=%c%s%c;main()
{printf(f,34,f,34,10);}%c";
main(){printf(f,34,f,34,10);}
this solution simply copies the whole source code that is written in main again in some pointer variable and prints it! whats the sense of doing that? :o
To solve the problem. It requires a little tweaking to be standard C++ code, of course.Quote:
whats the sense of doing that?
It is not residing in memory, unless you read from the source file, which you do not want to do. You forgot that the source code is compiled into object code.Quote:
since the source code that we are making is residing in memory
So now will you tell me how to do that?or like that day you will start giving answer in round about manner??
As in tweak the example to be standard C++?Quote:
So now will you tell me how to do that?
And i know the source code is compiled into object code. But will you please tell me how will the object code be build??if we are making the source code for the 1st time.That means during compilation there's no .obj file on hard disk!i hope you getting my point??the object file that doesn't exist at all..can we assign it's address to some file pointer?? ;)
It will do if it's not following the rules. I just want to do the job of printing the source code..
This is just the job of the compiler.Quote:
But will you please tell me how will the source code be build??if we are making the source code for the 1st time.That means during compilation there's no .obj file on hard disk!
No. You are heading in the wrong direction. To begin with, the object code is different from the source code.Quote:
the object file that doesn't exist at all..can we assign it's address to some file pointer?
Then you either write a true quine that prints its own source code without any file I/O at all, or you simply provide a copy of the source file along with the program, and read from that file.Quote:
It will do if it's not following the rules. I just want to do the job of printing the source code..
I presume you are discussing the objective of producing a program that prints itself, and the "chicken and egg problem" caused by that? Having source code print itself is pretty pointless in itself - it's only useful in "academic" circles. And somehow, the source file MUST know it's own content to be able to print it. It's a bit like asking a painter paint himself doing a self-portrait of himself - he must then first paint a self-portrait, right [although, technically, this can be painted onto the same canvas as the painting of himself painting said-self portrait. But just like this example, if you want the source code to print itself, it first needs to have the source code.Quote:
Originally Posted by chottachatri
--
Mats
A compiler takes C/C++ code as input, and outputs object code that can be run on the CPU directly. Object code is basically a string of very low level CPU instructions. It looks nothing like and does not include the original source code. The most you can get if you try really hard is probably printing out an assembly version of your program, by reading the memory directly, and disassemble the opcode. I am not sure if even THAT is possible.Quote:
And i know the source code is compiled into object code. But will you please tell me how will the object code be build??
A compiler converts source code into object code. It's not a one-to-one relationship, however. Therefore, you cannot convert the object code back to the source code (actually there are programs that convert object code into C/C++, but it's probably not what you want, because the resulting source code will look nothing like your original code, just something equivalent in functionality).Quote:
if we are making the source code for the 1st time.That means during compilation there's no .obj file on hard disk
Let the compiler be a function "C(s) = obj" where s is your source code, and obj is the resulting object code. The function is many-to-one, therefore, there exists no inverse function that converts obj back to your starting s.
But this has no useful purpose in a real-world application. Interviewers should be more concerned with asking questions that are relevent to the job.Quote:
Originally Posted by vart
The "Classical" education from some good University is useful in a real-world application. But instead of asking question what courses you have accomplished- they can ask questions that will show what you have actually learned...Quote:
Originally Posted by cpjust
They can see whether or not you have a "classical" education by looking at your resume. They should be asking you intelligent questions about situations that you will encounter on the job and which help validate your work experience.Quote:
Originally Posted by vart
I'd say that actual knowledge and experience are worth a lot more than fancy degrees that just prove you paid a lot of money for a piece of paper.
I could write in my resume whatever I want. Interviewer should make sure - all that is written in the resume is actually true, or close to the trueth...Quote:
They can see whether or not you have a "classical" education by looking at your resume
I can write in the resume I have studied assembler in the University. Which it true. But it was a small course take more than 15 years ago... Since then I never programed in asm... Do you think I could answer any question about assembler now?
So the resume is just a starting point for the interview.
Yeah, that's exactly what I mean. They ask should questions to verify a person's skills. If they really want to discriminate against people without a certain type of education, they can just ask to see your degree or contact the school to verify...Quote:
Originally Posted by vart
why dont you use like
get the window handle of the compiler , or ide or what ever your executable is called
then use SendMessage WM_GETTEXT , and read every line in to a buffer
Handle HandleofCompiler;
FindWindow(NULL,"your compiler name"):
char buffer[32];
if this returns ok , then you have a handle
now you can use SendMessage(HandleofCompiler , WM_GETTEXT , 0 , LPARAM(buffer));
altho i am not sure how you would move to the next line ,,,
Because that would only work if you know which IDE you're using, assuming you're using one at all, and it would only work when you run the program from the IDE, which you'd only do when writing it.Quote:
Originally Posted by Anddos
Besides the obvious solution, read the source file and print it.
The other and easy too, solution is write the program first. Then declare a string variable containing the
same text as your program. Now your source is changed to a kind of mirror image. The same source text exists twice. One in original form, and other in string form. Now just print that string twice, by whatever means. A little trick may be needed. But thats it. :)
work when you run the program from the IDE, which you'd only do when writing it.
not true , you could run the program exe from any directory , not just from the run menu of the compiler ,
all you would have todo is have the compiler open showing the source code ,
do you mean you want to view the source code to output even with the compiler/ide closed?
maybe make some kind of decrytor ,
like if the varible is a int in your program , then use sizeof() to confirm it
then output int , but wont be able to get the varible name
or even better -- don't waste your time with nonsense like this. It has absolutely no purpose and your time would be better spent doing just about anything else.Quote:
Originally Posted by Anddos
cpjust what kind of reply is that , i am only trying to help , keep your comments to your self
The best you can get if trying to reverse engineer your program (which you need to do if you don't have the source handy), is to get assembly.Quote:
Originally Posted by Anddos
Meaning no variable names, no function names, etc, etc.
It's pretty meaningless.
I'm trying to help too -- helping people from writing useless programs. ;)Quote:
Originally Posted by Anddos
In any case, Laserlight already answered the question a while ago:
http://en.wikipedia.org/wiki/Quine_%28computing%29
Actually one of the challenges on this site is to write a quine. There's even a nice solution to it.
http://www.cprogramming.com/challeng...elf_print.html
Actually quines do have some uses. Some viruses that are built with showing off in mind (core wars) will make copies of themselves by outputting their own source code into a text folder and compiling itself. Well you can kind of call that a use...
Wouldn't it be a hell of a lot easier to just copy the existing executable rather than recompile itself? :confused:Quote:
Originally Posted by A10
I doubt if they still remain quines but for one thing they can make some changes in their source and then compile!
A kind of self evolving virus :)
Not if you are doing the original worm (as the son of the NSA director did in the late 1990's or so), which walked across machine architectures, as long as the machine had a version of Unix installed, it would attempt to compile and install itself. Since machines where of differing architectures, you couldn't just copy the binary...Quote:
Originally Posted by cpjust
--
Mats
So you mean the virus telnets into a machine, finds the compiler, spits out it's source code, compiles and remotely executes the new version?Quote:
Originally Posted by matsp
Something along those lines, yes.Quote:
Originally Posted by cpjust
--
Mats
That's not NEARLY as cool though :cool:Quote:
Originally Posted by cpjust