递归函数DigitSum(n)，输入一个非负整数，返回组成它的数字之和

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

typedef unsigned int uint;

uint DigitSum(uint n)
{
assert(n);
if (n < 10)
{
return n;
}
else
{
return n % 10 + DigitSum(n / 10);
}
}

int main()
{
uint number = 0;
scanf("%u", &number);
printf("%u", DigitSum(number));
system("pause");
return 0;
}