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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <stddef.h>
  4.  
  5. typedef struct __attribute__((packed))
  6. {
  7.     char a;
  8.     short b;
  9.     int c;
  10. } my_struct;
  11.  
  12. char buff[50];
  13.  
  14. int main(void) {
  15. 	my_struct s;
  16. 	s.a = 1;
  17. 	s.b = 2;
  18. 	s.c = 3;
  19.  
  20. 	memcpy(buff, &s, sizeof(s));
  21.  
  22. 	short value = 0;
  23. 	memcpy(&value, buff + offsetof(my_struct, b), sizeof(value));
  24.  
  25. 	if (value == 2)
  26. 	{
  27. 		value = 10;
  28. 		memcpy(buff + offsetof(my_struct, b), &value, sizeof(value));
  29. 	}
  30.  
  31. 	memcpy(&s, buff, sizeof(s));
  32.  
  33. 	printf("%d\r\n", s.b);
  34.  
  35. 	// This is a no-no?
  36. 	my_struct *ptr = (my_struct *)buff;
  37. 	ptr->b = 1337;
  38. 	memcpy(&s, buff, sizeof(s));
  39. 	printf("%d\r\n", s.b);
  40.  
  41. 	return 0;
  42. }
  43.  
Success #stdin #stdout 0s 5456KB
comments (?)
stdin 
Standard input is empty
stdout 
10
1337
https://ideone.com/fwU1Ke
language:
C (gcc 8.3)
created:
2 years ago
visibility:
public

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