折半查找法是效率较高的一种查找方法。假设有已经按照从小到大的顺序排列好的五个整数a0~a4，要查找的数是X，其基本思想是: 设查找数据的范围下限为l=1，上限为h=5，求中点m=(l+h)/2，用X与中点元素am比较，若X等于am，即找到，停止查找;否则，若X大于am，替换下限l=m+1，到下半段继续查找;若X小于am，换上限h=m-1，到上半段继续查找;如此重复前面的过程直到找到或者l>h为止。如果l>h，说明没有此数，打印找不到信息，程序结束。(The method of binary search is one of the most efficient methods. Hypothesis has already ranked in accordance with the order of the growing up five integers a0 ~ a4, to find the number is X, its basic idea is: the scope of the data set to find the lower limit for l = 1, up to h = 5, strives for the midpoint m = (l + h) / 2, with X compared with neutral element am, if X is equal to the am, is found, stop looking for; Otherwise, if X is greater than am, replace the lower bound l=m+ 1, and continue to find it in the lower half; If X is less than am, change the upper limit h is equal to m minus 1, and continue to find it in the first half; Repeat the previous process until you find or l> h. If l> h, you don't have this number, print can't find the information, the program ends.)