C how to program; 习题3.34 打印一个空心正方形
1 #include<stdio.h> 2 int main(void) 3 { 4 int x,i,j; 5 printf("Please input the length(1-20): \n"); 6 scanf("%d",&x); 7 for (i=1;i<=x;i++) 8 printf("* "); 9 printf("\n"); 10 for (i=1;i<=x-2;i++) 11 { 12 printf("* "); 13 for (j=1;j<=x-2;j++) 14 { 15 printf(" "); 16 } 17 printf("*\n"); 18 } 19 for (i=1;i<=x;i++) 20 { 21 printf("* "); 22 } 23 printf("\n"); 24 return 0; 25 }