C语言 int类型转换成二进制

　　使int n依次和2的次方进行与操作（&），得知每个位是0还是1，并且写入字符数组，返回写有数字二进制信息的字符指针。

　　

#include <stdio.h>
#include <stdlib.h>

char *toBinary(int num)
{
    char *binary = (char *)malloc(sizeof(char) * 33);
    int flag = 1;
    int i;

    for (i = 31; i >= 0; i--)
    {
        if (num & flag)
        {
            binary[i] = '1';
        }
        else
        {
            binary[i] = '0';
        }
        flag<<=1;
    }
    binary[32] = '\0';

    return binary;
}

int main()
{
    char *tmp;
    for (int i = -16; i <= 16; i++)
    {
        tmp = toBinary(i);
        printf("%d:\t%s\n", i, tmp);
        free(tmp);
        tmp = NULL;
    }

    return 0;
}

#include <stdio.h>#include <stdlib.h>
char *toBinary(int num){char *binary = (char *)malloc(sizeof(char) * 33);int flag = 1;int i;
for (i = 31; i >= 0; i--){if (num & flag){binary[i] = '1';}else{binary[i] = '0';}flag<<=1;}binary[32] = '\0';
return binary;}
int main(){char *tmp;for (int i = -16; i <= 16; i++){tmp = toBinary(i);printf("%d:\t%s\n", i, tmp);free(tmp);tmp = NULL;}
return 0;}