C语言：用递归函数DigitSum(n)实现输入1729，输出sum=1+7+2+9=19的值

#include<stdio.h>
#include<stdlib.h>

int DigitSum(int n)
{
int sum = 0;
if (n > 0)
{
sum = n % 10;
sum = sum + DigitSum(n / 10);
}

return sum;
}

int main()
{
int num = 1729;
int ret = DigitSum(num);
printf("%d\n", ret);
system("pause");
return 0;
}