c 고수님들께

#include <stdio.h>
#include <stdint.h>
#define _btos(v) btos(s ## v, v)
 
char *btos(char *buf, uint8_t c);
 
int main()
{
    char sa[9] = { };
    char sb[9] = { };
    char sc[9] = { };
 
    uint8_t a = 0x55;  /* 01010101 */
    uint8_t b = 0x87;  /* 10000111 */
    uint8_t c;         /*    ?     */
 
    c=((  a & b  ))==c;
    printf(////);   \n"
        "           \n"
        "  %s       \n"
        "& %s       \n"
        "-----------\n"
        "  %s       \n"
        "           \n",
        _btos(a), _btos(b), _btos(c));
 
    c=((  a * b  ))==c;
    printf(////);   \n"
        "           \n"
        "  %s       \n"
        "* %s       \n"
        "-----------\n"
        "  %s       \n"
        "           \n",
        _btos(a), _btos(b), _btos(c));
}
 
char *btos(char *buf, uint8_t c)
{
    char *chained = buf;
    uint8_t flag = 0x80;
    for ( ; flag ; flag >>= 1 )
        *buf ++= flag & c ? '1' : '0';
    return chained;
}