打印1~100之间7的倍数的数的个数，及其总和

#include <stdio.h>
int main()
{
    int a[20],b=0,c,j=0,sum=0;
    for (int i = 1; i <= 100; i++)
    {
        if (i % 7 == 0)
        {
            b++;
            a[b] = i;
        }
        c = b;
    }
    for (b; b > 0; b--)
        sum = sum + a[b];
    printf("1~100之间7的倍数的数有%d个，总和为%d", c, sum);
}