this is a gcc file, you can download it and learn its usetility, for further detail please look at t
源代码在线查看: f-0-20-17.c
#include struct sss{ int :0; int i2:20; int i3:17; }; static union u{ struct sss sss; unsigned char a[sizeof (struct sss)]; } u; int main (void) { int i; for (i = 0; i < sizeof (struct sss); i++) u.a[i] = 0; u.sss.i2 = 1048575.0; for (i = 0; i < sizeof (struct sss); i++) printf ("%x ", u.a[i]); printf ("\n"); u.sss.i3 = 131071.0; for (i = 0; i < sizeof (struct sss); i++) printf ("%x ", u.a[i]); printf ("\n"); return 0; }