C语言~输入不多于3位正整数。判断位数，从小到大写出

输入-9999 表示输入结束，输入0-999的整数参加排队，从小到大写出。

#include <stdio.h>

void main()
{
int a[100];
int i,j,k,n=0;

while (1)
{
printf("Please enter data 0 to 999. if finish, enter -9999 \n");
scanf("%d",&a[n]);
if ( a[n] == -9999) break;
if ( a[n] > 999 ) { printf("too big !\n"); continue;};
if ( a[n] < 0) { printf("must >= 0 !\n"); continue;};
n = n + 1;
}

for (i=0;i<n-1;i++)
for (j=i+1;j<n;j++)
if (a[i] > a[j]) { k=a[i];a[i]=a[j];a[j]=k;};

for (i=0;i<n;i++) printf("%d ",a[i]);
}

#include "stdio.h"
void main()
{ int a,i,j,s[3],x;
printf("shuruyigexiaoyusanweideshu:\n");
scanf("%d",&a);
for(i=0;a!=0;i++)
{s[i]=a%10;
a=a/10;}
printf("weishushi:%d\n",i);
for(j=0;j&