c bit field

定义data structure时定义成员变量的bit宽度

#include <stdio.h>
#include <stdint.h>

typedef struct a_s
{
    unsigned int num1:1;
    unsigned int num2:1;
}a_t;

int main() {
    printf("sizeof a_t %d\n", sizeof(a_t));
    return 0;
}  // main end

result: sizeof a_t 4

参考 http://www.tutorialspoint.com/cprogramming/c_bit_fields.htm