what is the difference between struct {0} and memset 0 [duplicate]

by

None. The final outcome is that both initialize structure members to 0.

C99 Standard 6.7.8.21

If there are fewer initializers in a brace-enclosed list than there are elements or members of an aggregate, or fewer characters in a string literal used to initialize an array of known size than there are elements in the array, the remainder of the aggregate shall be initialized implicitly the same as objects that have static storage duration.

Your structure A is an aggregate and above rule applies to it. So all the structure members are initialized with value same as for static storage duration. Which is 0.

C99 Standard 7.21.6.1 The memset function: 

void *memset(void *s, int c, size_t n);

The memset function copies the value of c (converted to an unsigned char) into each of the first n characters of the object pointed to by s.

In simple words all the members including the alignment/padding bits in object of your structure A are set to 0.

Note that only difference between the two constructs in C is that memset sets the alignment/padding to 0 as well, while the aggregate initialization only guarantees that your structure members are set to 0.

In either case you do not have access to the alignment/padding bytes through convention language constructs and hence both get you the same effect.

More Related Contents:

  1. Access violation reading data from binary file into struct in C
  2. typedef struct vs struct definitions [duplicate]
  3. How to initialize a struct in accordance with C programming language standards
  4. How can I correctly assign a new string value?
  5. Difference between a Structure and a Union
  6. Pointer to pointer of structs indexing out of bounds(?) when I try to index anything other than zero
  7. How to define a typedef struct containing pointers to itself?
  8. Opaque C structs: various ways to declare them
  9. C – function inside struct
  10. Assign one struct to another in C
  11. The initialization of static variables in C
  12. C typedef of pointer to structure
  13. How to initialize const in a struct in C (with malloc)
  14. Trouble Understanding MPI_Type_create_struct
  15. Why does “typdef struct { struct S *s; } S;” containing a pointer to same type compile?
  16. Are “malloc(sizeof(struct a *))” and “malloc(sizeof(struct a))” the same?
  17. What does “request for member ‘*******’ in something not a structure or union” mean?
  18. How is the result struct of localtime allocated in C?
  19. How to initialize a structure with flexible array member
  20. memcpy vs assignment in C
  21. Empty structure in C
  22. Why declare a struct that only contains an array in C?
  23. How to include a dynamic array INSIDE a struct in C?
  24. Initializing a struct to 0
  25. Anonymous union within struct not in c99?
  26. C Typedef – Incomplete Type
  27. How do you use offsetof() on a struct?
  28. How does C return a structure? [duplicate]
  29. Returning a struct pointer
  30. Why does static initialization of flexible array member work?

Leave a Comment