二分搜索函数

int search(char key, char a[]) {
	int mid=0, begin=0, end=strlen(a);
	//printf("key=%c\n", key);
	while (begin<end)
	{
		mid = (begin + end)>> 1;
		if (a[mid] >= key) end = mid;
		else begin = mid + 1;
	}
	if (a[begin] == key) return 1;
	
	return 0;
}