编辑代码

#include <stdio.h>

typedef  union 
{
    int u;
    struct 
    {
        int a    :4;
        int b   :4;
    }bits;

}adc;

int main()
 {
     adc py;
py.u = 0;

py.bits.a = 7;

py.bits.b = 0;

printf("py.u = %d\n",py.u);
	return 0;
}