如何写出一个空心正方形新解法

 

#include "stdio.h"void add(bianchang){int i,j,c; c=bianchang; for(i=1;i<=c;i=i++) {for(j=1;j<=c;j=j++)  {if(i==1||i==c)  printf("*");  else {if(j==1||j==c)  printf("*");  else printf(" ");}}   printf("\n");}}void main(){int n; printf("input bianchang please:"); scanf("%d",&n); while(n>0) {  add(n);  printf("input bianchag please:");  scanf("%d",&n);}}