2. 打开程序Cprog012.C，完成其中的函数fun2(int a[ ], int n, int b[ ], int c[ ])，实现：
(1)将数组a中大于-20的元素，依次存放到数组b中；
(2)将数组b中的元素按照从小到大的顺序存放到数组c中；
(3)函数返回数组b中的元素个数。
#include <string.h>
#include <conio.h>
#include <math.h>
#include <stdio.h>
int fun2(int a[],int n,int b[],int c[])
{
/**/
/**/
}
void main()
{ int n = 10, i, nb;
int aa[10] = {12, -10, -31, -18, -15, 50, 17, 15, -20, 20};
int bb[10], cc[10];
clrscr();
printf("There are %2d elements in aa.\n", n);
printf("They are: ");
for(i=0; i<n; i++) printf("%6d", aa[i]);
printf("\n");
nb = fun2(aa, n, bb, cc);
printf("Elements in bb are: ");
for (i=0; i<nb; i++) printf("%6d", bb[i]);
printf("\n");
printf("Elements in cc are: ");
for(i=0; i<nb; i++) printf("%6d", cc[i]);
printf("\n");
printf("There are %2d elements in bb.\n", nb);