The meaning of packed in C language

This article mainly introduces "the meaning of packed in C language". In daily operation, I believe many people have doubts about the meaning of packed in C language. Xiaobian consulted various materials and sorted out simple and easy operation methods. I hope to help you answer the doubts about "the meaning of packed in C language"! Next, please follow the small series to learn together!

A Study on the Meaning of Packed

In C, a struct declaration can be modified with__attribute__ ((__packed__)), indicating that the memory space occupied by the compressed struct is placed so that the latter element is placed next to each other. See the example program below:

#include

#include

struct upack

{

char s;

int i;

};

struct packs

{

char s;

int i;

}__attribute__ ((__packed__));

int main(int argc, char *argv[])

{

printf("size of packs is %d and upack is %dn",sizeof(struct packs),sizeof(struct upack));

printf("size of int is %dn",sizeof(int));

printf("size of char is %dn",sizeof(char));

struct upack upk;

printf("address of upk is %dn",&upk);

printf("address of upk.s is %dn",&(upk.s));

printf("address of upk.i is %dn",&(upk.i));

struct packs pk;

printf("address of pk is %dn",&pk);

printf("address of pk.s is %dn",&(pk.s));

printf("address of pk.i is %dn",&(pk.i));

system("PAUSE");

return 0;

}

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