【C语言】不使用循环和判断语句，求出1-100之间所有数的和

//不使用循环和判断语句，求出1-100之间所有数的和
#include <stdio.h>
int fun(int n, int *sum)
{
*sum = *sum + n;
(n--) && (fun(n, sum));
return n;
}
int main()
{
int n = 100;
int sum = 0;
fun(n, &sum);
printf("%d\n", sum);
return 0;
}
<img src="http://img.blog.csdn.net/20150630155401858?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvZG91ZG91d2ExMjM0/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />