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

int BinarySearch(int *ar,unsigned num,int key)
{
	unsigned Upper,Lower,Mid;

	Lower=0;
	Upper=num-1;
	for (;;) {
		Mid=(Upper+Lower)/2;

		if (ar[Mid]==key) return Mid;
		if (ar[Mid]>key) {
			Upper=Mid-1;
		} else {
			Lower=Mid+1;
		}
		if (Upper<=Lower) {
			return -1;
		}
	}
}

void main()
{
	int ar[]={2,6,13,19,21,21,23,29,35,48,62,89,90,95,99,102,109,208,629};
	unsigned num;
	int key,idx;

	num=sizeof(ar)/sizeof(ar[0]);
	key=29;
	idx=BinarySearch(ar,num,key);
	if (idx == -1) {
		puts("찾는 값이 없습니다.");
	} else {
		printf("찾는 값은 %d번째에 있습니다.\n",idx);
	}
}