Execute any function before main [duplicate]

Answer 1

Is it possible to execute a function before main()

Yes it is possible if you are using gcc and g++ compilers then it can be done by using __attribute__((constructor))

Example:

#include 

void beforeMain (void) __attribute__((constructor));

void beforeMain (void)
{
  printf ("\nThis is before main\n");
}

int main ()
{
 printf ("\nThis is my main \n");
 return 0;
}