C语言给变量的某个位置1或清0例程

#include <stdio.h>

#define set_bit(val,bit)     ((val)|=(0x01<<bit))
#define clear_bit(val,bit)   ((val)&=~(0x01<<bit))

void main(void)
{
    unsigned char val=0x00;
    set_bit(val,3);
    printf("val=%02x\n",val);
    clear_bit(val,3);
    printf("val=%02x\n",val);
}