C语言二十一弹 --打印空心正方形

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
  int n = 0;
  while (scanf("%d", &n) != EOF)
  {
    for (int i = 0; i < n; i++)
    {
      for (int j = 0; j < n; j++)
      {
        if (i == 0 || j == 0 || i == n - 1 || j == n - 1)
        {
          printf("* ");//保持美感加入空格
        }
        else
        {
          printf("  ");//双空格
        }
      }
      printf("\n");//打印完一行换行
    }
  }
  return 0;
}