关于sizeof和size_t再次置顶

// sizeof.c -- uses sizeof operator
// uses C99 %z modifier -- try %u or %lu if you lack %zd
#include <stdio.h>
int main(void)
{
    int n = 0;
    size_t intsize;
  
    intsize = sizeof (int);
    printf("n = %d, n has %u bytes; all ints have %u bytes.\n",
         n, sizeof n, intsize );
         
    return 0;
}
结果：n=0, n has 2 bytes; all ints have 2 bytes.


修改后：
// sizeof.c -- uses sizeof operator
// uses C99 %z modifier -- try %u or %lu if you lack %zd
#include <stdio.h>
int main(void)
{
    int n = 0;
    size_t intsize;
  
    intsize = sizeof (int);
    printf("n = %d, n has %u bytes; all ints have %u bytes.\n",
         n, sizeof n, intsize );
         
    return 0;
}
结果：n=0, n has 0 bytes; all ints have 4 bytes.

为什么“n has 0 bytes”？