int shown as to take 8 bytes [duplicate]

问题

This question already has answers here:

Why isn't sizeof for a struct equal to the sum of sizeof of each member? (12 answers)

Closed 1 year ago.

I have taken code from https://www.geeksforgeeks.org/the-offsetof-macro/.

I ran the code in ide provided in gfg itself.

I have edited code a bit , sizeof(int) is showing 4 but it is shown to take 8 bytes in struct through offset

#include <stdio.h> 

#define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT)) 

typedef struct PodTag 
{ 
    int   i; 
    double d; 
    char  c; 
} PodType; 

int main() 
{ 
    printf("%ld", OFFSETOF(PodType, d) ); 

    getchar(); 
    return 0; 
} 

回答1:

The next field d requires 8 byte alignment. This means that 4 padding bytes are inserted between the fields.

On other architectures it might be different.

来源：https://stackoverflow.com/questions/54940026/int-shown-as-to-take-8-bytes