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  1. #include <stdio.h>
  2. #include <stdint.h>
  3.  
  4. struct foo
  5. {
  6. 	int padding1;
  7. 	unsigned char padding3;
  8. 	void* ptr;
  9. 	int padding2;
  10. };
  11.  
  12. struct foo* start_address(void* ptr)
  13. {
  14. 	intptr_t offset = (unsigned int)&((struct foo*)0)->ptr;
  15. 	return (struct foo*)(ptr - offset);
  16. }
  17.  
  18. int main(void) {
  19. 	struct foo test;
  20. 	printf("%p == %p\n", &test, start_address(&test.ptr));
  21. 	return 0;
  22. }
  23.  
Success #stdin #stdout 0s 2160KB
comments (?)
stdin 
Standard input is empty
stdout 
0xbf86bff0 == 0xbf86bff0
https://ideone.com/edE0R3
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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