How to execute code before and after main function

C++ trick

Table of contents

#include <stdio.h>
#include <stdlib.h>

void my_before_main(void) __attribute__((constructor));
void my_after_main(void) __attribute__((destructor));

void my_before_main_2(void) __attribute__((constructor));
void my_after_main_2(void) __attribute__((destructor(119)));

__attribute__((destructor(120))) void my_after_main_3(void) {
  printf("start after main 3\n");
  return;
}

// BOth attributes can be specified on the same function
void __attribute__((constructor)) __attribute__((destructor))
another_before_and_after_main() {
  printf("%s called before and after main()\n", __PRETTY_FUNCTION__);
}

void my_before_main(void) {
  printf("start before main\n");
  return;
}

void my_after_main(void) {
  printf("start after main\n");
  return;
}

void my_before_main_2(void) {
  printf("start before main 2\n");
  return;
}

void my_after_main_2(void) {
  printf("start after main 2\n");
  return;
}

int main(int argc, char *argv[]) {
  printf("start in main\n");
  return 0;
}