C语言入门：累加a个n构成的整数之和,求a+aa+aaa+…+aa…a(n个a)

#include<stdio.h>        //累加a个n构成的整数之和,求a+aa+aaa+…+aa…a(n个a)#include<math.h>int fn (int a, int n){int fn=0,item=a,i;for(i=1;i<=n;i++){fn+=item;item=item*10;}return fn;}int main(void){int sum=0,i,a,n;for(;;){    printf("请输入两个正整数a和n（输入0退出）:\n");    scanf("%d%d",&a,&n);if(a==0||n==0){printf("程序运行结束\n");break;}else if(a>0&&n>0){for(i=1;i<=n;i++)sum+=fn(a,i);}else{printf("输入错误!\n");continue;}printf("累加%d个%d构成的整数之和为%d\n",n,a,sum);sum=0;}return 0;}