2 编程，求s=1+12+123+1234+12345

2
编程，求s=1+12+123+1234+12345的值

代码如下：

#include <stdio.h>

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

int main()
{
    int i = 1;
    int sum = 0;
    for (;i<=5;i++)
    {
        sum += fun(i);
    }
    printf("1+12+123+1234+12345=%d\n",sum);
    return 0;
}