十进制转二进制 c语言中十进制转二进制显示小工具的实现代码

/*
 * =======================================================================
 *
 *       Filename:  dec2bin.c
 *
 *    Description:  dec to binary show
 * =======================================================================
 */
#include <stdio.h>
#include <stdlib.h>

#define HALF_CHAR 4

void bit_print(int bit_num, int a);

int main(int argc, char **argv)
{
    if (argc != 3) {
        printf("use: name num dec\n");
        exit(1);
    }

    bit_print(atoi(argv[1]),atoi(argv[2]));
    printf("done!\n");

    return 0;
}

void bit_print(int bit_num, int a)
{
    int i;
    int n = sizeof(char) * 8 * bit_num;

    int mask = 1 << (n - 1);

    printf("Num %d Binary is : 0B", (bit_num * 8));
    for (i = 1; i <= n; ++i) {
        putchar(((a & mask) == 0) ? '0' : '1');
        a <<= 1;
        if (i % HALF_CHAR == 0 && i < n)
            putchar(' ');
    }
    putchar('\n');
}