c语言二分法如何实现查找数组元素

#include<stdio.h>

//二分法实现数组查找

//

int recurbinary(int *a, int key, int low, int high)

{

    int mid;

    if(low > high)

        return -1;

    mid = (low + high)/2;

    if(a[mid] == key) return mid;

    else if(a[mid] > key)

         return recurbinary(a,key,low,mid -1);

    else

         return recurbinary(a,key,mid + 1,high);

}

int binary( int *a, int key, int n )

{

    int left = 0, right = n - 1, mid = 0;

    mid = ( left + right ) / 2;

    while( left < right && a[mid] != key )

    {

        if( a[mid] < key ) {

            left = mid + 1;

        } else if( a[mid] > key ) {

            right = mid - 1;

        }

        mid = ( left + right ) / 2;

    }

    if( a[mid] == key )

        return mid;

    return -1;

}

int main(void)

{

int a[10] = {2,4,6,8,10,12,14,16,18,20},t,k,f;

scanf("%d",&t);

k = recurbinary(a,t,2,20);

f = binary(a,t,10);  //非递归算法

if(k == -1){

printf("不存在此数\n");

}else{

printf("%-5d是数组第%d个元素\n%-5d数组的第%d个元素",k,k+1,f,f+1);

}

return 0;

}