第四章 Mongodb聚合函数 插入 测试数据 ;j<;j++){ for(var i=1;i<3;i++){ var person={ Name:"jack"+i, Age:i, Address:["henan","wuhan"], Course:[ {Name:"shuxue",Score:i}, {Name:"wuli",Score:i} ] } db.DemoTest.Person.in…

目录 一.迭代器 二.yield生成器 三.装饰器 四.递归 五.基础算法 迭代器 #1.在不使用for循环的情况下 li = [11 ,22, 33, 44] #count = len(li) #start = 0 #while count > start: # print(li[start]) # start += 1 #while 使用索引进行操作,所有的其他预言,都支持while #for item in li: # print(item) #for循环本质 #1.创建一个特殊的东西(迭…

为了便于后续的读取处理,这里就将信息保存在xml文件中,想到得到的文件如下: 1 <?xml version="1.0" encoding="utf-8"?> 2 <orderlist> 3 <order> 4 <customer>姓名1</customer> 5 <phone>电话1</phone> 6 <address>地址1</address> 7 &l…

第四章 Mongodb聚合函数 插入 测试数据 for(var j=1;j<3;j++){ for(var i=1;i<3;i++){ var person={ Name:"jack"+i, Age:i, Address:["henan","wuhan"], Course:[ {Name:"shuxue",Score:i}, {Name:"wuli",Score:i} ] } db.DemoTe…

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, two is written as II in Roman numeral, just two one's added together. Twelve is written as, XII, which i…

In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., N), with one additional edge added. The added edge has two different v…

整型 int __author__ = 'Tang' # 将字符串转换为数字 a = " b = int(a) # 前面是0的数转换,默认base按照十进制 a = " b = int(a) # 通过base,按照指定进制转换为十进制 a = " b = int(a,base=16) c = int(a,base=8) # bit_length() 表示这个数字的二进制至少用几位来表示 a = 15 b = 16 c = a.bit_length() d = b.bit_le…

本文介绍3种TCP连接异常的情况. 1.server端没有启动,client尝试连接 ./client dial failed: dial tcp 127.0.0.1:8080: connect: connection refused 通过tcpdump抓包,可以看到当server没有启动的时候,client向server8080端口发送数据后,client端会收到RST. 2.client端读数据,突然异常退出或直接close连接 2.1 准备 server server等待连接,如果有cli…

zombodb 暴露所有es _cat/ api 为视图,我们可以通过视图方便的查询es 的信息,默认在zdb的schema 中 包含的视图 几个方便的view 查看索引统计信息zdb.index_stats select * from zdb.index_stats; -[ RECORD 1 ]----+------------------------------------------- alias | postgres.public.products.idxproducts-17176 i…

非线程安全 public class UnSafeThreadLocalDemo { private int count = 0; public static void main(String[] args) { UnSafeThreadLocalDemo unSafeThreadLocalDemo = new UnSafeThreadLocalDemo(); for (int i = 0; i < 5; i++) { int finalI = i; new Thread(new Runnabl…