Why am i getting segfault in below code?

Question

I am writing the code without main function.

#include<stdio.h>
_start()
{
int a=10,b=20,res;
res=a+b;
printf("Res = %d\n",res);
}

Compiling : cc -nostartfiles filename.c

Output:

Res = 30
Segfault

Comments

Without _exit(0); the program will compile, but there will be Segmentation fault while running it. So you need to add _exit(0) at the end of _start function :)

Answer 1

Without _exit(0); the program will compile, but there will be Segmentation fault while running it.

Very Good article related to how main() get called

_start() use a exit(main());
Return value of main is passed to exit() which terminates our program.

Here we do not have main(), we have to explicitly call the _exit(0);