实验6-3 使用函数求特殊a串数列和 (20 分)

#include <stdio.h>

int fn(int a, int n);
int SumA(int a, int n);

int main()
{
    int a, n;

    scanf("%d %d", &a, &n);
    printf("fn(%d, %d) = %d\n", a, n, fn(a, n));
    printf("s = %d\n", SumA(a, n));

    system("pause");
    return 0;
}

/* 你的代码将被嵌在这里 */
int fn(int a, int n) {
    int sum = 0;
    for (int i = 0; i < n; i++)
        sum = sum * 10 + a;
    return sum;
}

int SumA(int a, int n) {
    int sum = 0;
    for (int i = 1; i <= n; i++)
        sum = sum * 10 + a * i;
    return sum;
}

函数一定要有返回值，return sum;