/*you cannot change anything from here below*/
main()
{
exit(0);
}
/*you cannot change anything from here up*/
This was asked during an interview.
I was told to print something on console.
anybody?
views:
285answers:
8
+17
A:
weird question...
int main(void)
{
printf("hello");
return 0;
}
#define main int lol
/*you cannot change anything from here below*/
main()
{
exit(0);
}
/*you cannot change anything from here up*/
tenfour
2010-08-20 11:38:04
+1 for 'weird question' (and the solution)
Pavel Radzivilovsky
2010-08-20 11:40:30
Not that it's relevant, but I don't see how that proves the competence of the applicant.
Tamás Szelei
2010-08-20 11:41:25
Maybe successful applicants will be required to use this technique in production
Tim Robinson
2010-08-20 11:42:39
Maybe it tests if the applicant is able to do printf-debugging without touching the code? If he is aware of the possibilities of the preprocessor? Or whatever else. Though a competent applicant not being aware about this could learn it within a few hours, even when he hasn't an immediate answer...
Secure
2010-08-20 14:53:01
+3
A:
One implementation defined way would be to use the pragma directives to print during compilation.
#pragma message "Compiling " __FILE__ "..."
Or, you could do this with some macros and a printf (but not without introducing UB in some aspect or the other) at runtime.
#define exit(x) printf("Hello, world!")
int main() {
exit(0);
return 0; /* if pre-C99 */
}
dirkgently
2010-08-20 11:43:13
@dirkgently - because "it works on my compiler" doesn't necessarily mean "it works"?
Steve314
2010-08-20 12:47:07
@Steve314: I think I made it clear that there is no conforming way of doing it (note the part about UB).
dirkgently
2010-08-20 13:51:57
A:
#include <stdio.h>
#pragma message("Some foobar")
#error This is an error message
int main()
{
exit(0);
}
I think the interviewer wanted to know if you're aware of the #error directive ... just my 2 cents.
celavek
2010-08-20 11:44:39
hahaha he got pissed at you for giving valid solutions to his ridiculous interview question :P this must have been a fun interview. let us know if you get / accept the job :)
tenfour
2010-08-20 11:49:25
Strictly speaking, the question asks "print something to the console" - the simplest way to do that would be "echo something". Don't write code if you've already got the right tool compiled and installed on millions of machines.
Douglas
2010-08-20 12:10:19
A:
Most answers involve the #define c-preprocessor instruction to change what the program means. Most compilers also support something like
#pragma startup foo()
details depend on the compiler vendor. You can make code run BEFORE main(*) is called that way.
Ian
2010-08-20 11:46:27
+15
A:
Really surprised that nobody posted this yet:
#include <stdio.h>
#if 0
/*you cannot change anything from here below*/
main()
{
exit(0);
}
/*you cannot change anything from here up*/
#endif
int main()
{
printf("Hello, World!");
return 0;
}
Prints at runtime and no undefined behavior whatsoever.
Tyler McHenry
2010-08-20 11:52:56
A:
#define exit(x) (printf("Bye"))
int main(int argc,char* argv)
{
exit(0);
getchar();
return 0;
}
fahad
2010-08-21 09:45:38