有15个数按由小到大顺序放在一个数组中，输入一个数，要求用折半查找法找出该数是数组中的第几个元素的值，如果该数不在数组中，则打印出无此数-15 the number of small to large order placed by an array, enter a few, require half the number of search method is to identify the array elements in the first few values, if the num