On which version of C following code will compile fine?

Asked Oct 10 '16 at 07:14

Active Oct 10 '16 at 07:19

Viewed 58 times

Does anybody know on which version of C this code will not throw compilation error ?

#include <stdio.h>

int main(){
    int y;
    y = f();
}

As per my knowledge of C programming language this code should not compile. Since a function must not exist without it's definition. But, my teacher said the above code should compile in C language and it will throw error at run time. She also suggest that C compilers check for the definition at the run time.

I had tried on C90 and C99 environment in Codeblock with GCC compiler, but result was compile time error as i presumed.

Help me out with this mess. -> When does a C compiler check for definition of program ? -> Does above code is possible to pass through compilation process and throw error at run time in any old version of C or any older C compiler. -> Suggest me if i have some misconceptions.

Thanks for helping me out.

edited Oct 10 '16 at 07:19

asked Oct 10 '16 at 07:14

lifeisshubh

No that can't run, but that can compile. If not declared a function is as been declared as returning `int` and taking an unknown number of arguments, of course to run you need a definition of it. – Jean-Baptiste Yunès Oct 10 '16 at 07:19
But i am not able to compile it on GCC C compiler, it is throwing compiler time error that definition should be there. I have reedited the question. please help me out. – lifeisshubh Oct 10 '16 at 07:24
1

It compiles (in C89 and earlier standards) but it won't link unless you provide a definition `f()`. – Klas Lindbäck Oct 10 '16 at 07:29
Thanks for helping me out. – lifeisshubh Oct 10 '16 at 07:32

On which version of C following code will compile fine?

0 Answers0