编写一个函数unsigned fun(unsigned w),w是一个大于10的数,如果
w是n位数则返回后n-1位的数作为函数值返回.如w 是2345返回345
#include <stdio.h>
#include <math.h>
unsigned fun(unsigned w);
void main()
{
int x;
printf("input x:\n");
scanf("%u",&x);
printf("%u-----%u\n",x,fun(x));
getch();
}

unsigned fun(unsigned w)
{
unsigned x=0,t=0;
while(w)
{
x=w%10;
t++;
}
return(w-x*10^t);
}
如何用递归啊??