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

unsigned int q(unsigned int x)  //求出几位数字
{
    unsigned int i = 1 , j = 10;

    if(x < j)
        printf("%d是%d位数字.\n",x,i);
    else
    {
        while(x >= j)
        {
            j *= 10;
            i++;
        }
        printf("%d是%d位数字.\n",x,i);
    }
    return i;
}

void m(unsigned int arr[],unsigned int j, unsigned int m)   //分别输出每一位数字
{
    int i;
    unsigned int x = 10, y = 1;
    for(i = j-1; i >= 0; i--)
    {
        arr[i] = m % x / y;
        x *= 10;
        y *= 10;
    }
    for(i = 0; i < j; i++)
    {
        printf("%d, ",arr[i]);
        if((i + 1) % 5 == 0)
        {
            printf("\n");
        }
    }
    printf("\n");
}

unsigned int tiao(unsigned int a[], unsigned int x)    //按逆序输出各位数字
{
    unsigned int b = 0 , c = 1;
    for(int i = 0; i < x; i++)
    {
        b += a[i] * c;
        c *= 10;
    }
   
    return b;
}
int main()
{
    unsigned int x , y , z , e;
    unsigned int ar[10] = {0};
    printf("输入数字(0-1000000000) : ");
    while((y = scanf("%d",&x)) != 1 || x < 0 || x > 1000000000)
    {
        if(y != 1)
            scanf_s("%*s");
        printf("请正确输入数字(0-1000000000) : ");
    }

    z = q(x);
    m(ar,z,x);
    e = tiao(ar,z);
    printf("%d\n",e);
    system("pause");
    return 0;
}

都真牛...