what is vlookup function

distribution In short, when the site opened CDN, users visit the site, not directly to the site of the original server, but a server distributed to your nearest server node, because the server close to you, so access speed or download speed will be faster. Do you remember the previous introduction of the computer Pepsi network to set up DNS? Also mentioned in the DNS server address must fill out the nearest to your IP, which is the nearest principl

Web crawler is a program, mainly used in search engines, it will be a site of all the content and links to read, and establish the relevant full-text index into the database, and then jump to another site. Looks like a big spider.When people search for keywords on the web (such as Google), it is actually better than the content in the database to identify the user. The quality of the Web crawler determines

sequence of a large-scale adjustment. If it is object-oriented, only with the change of the Board object on the line, the board system to save black and white on both sides of the game, simple backtracking can be, and the display and rule judgment is not to be taken into account, while the entire function of the object call sequence has not changed, the change

distinguish: compile-time and run-time.ID obj = someinstance;if ([obj Iskindofclass:someclass]) {SomeClass *classspecifiedinstance = (SomeClass *) obj;}(2) Dynamic bindingDynamic binding is seemingly more difficult to remember, but in fact it is very simple, just remember the keyword @selector/sel. First look at "functions", for some other static language, such as C + +, generally at the time of compiling

What is a hook? what is the function of hook? everyone knows that almost all php video lectures, including books, do not mention the Hook concept at all. However, it is often used in actual projects, so sometimes I feel that the g

Twisted (1) -- What is asynchronous, twisted -- What is asynchronous I have long wanted to write an article about python's two asynchronous libraries, twisted and tornado. When developing python tcpserver, we usually only use three libraries, twisted, tornado, and gevent. The efficiency of asynchronous libraries repres

) are not interfering with each other, and cannot be mixed together. Also give the behavioral layer a "fallback", taking into account what happens if your users disable Javascript? is not a webpage can also function normally.Amount Said a long time found are some of the theoretical things, as some basic ideas, specific people in the process of continuous practice

does not involve design patterns, architecture, efficiency and other issues. Or Google first, to see what the Web front-end development, Web backend development, respectively. Web front-end: As the name suggests is to do the front-end of the web. What we are talking about here is the front end of the web, where the

Dojo is an open source DHTML (Dynamic HTML) implemented by JavaScript)Toolkit. What can dojo do ?? 1. It makes it easier for developers to add dynamic capabilities to web pages. You can also use dojo in other environments that support JavaScript; 2. With the components provided by dojo, developers can improve the availability and interaction of Web applications; 3. dojo largely shields the differences b

Combiners programming1. Each map generates a large amount of output, and the Combiner function is to do a merge on the map end to reduce the amount of data transferred to reducer.2.combiner is the most basic implementation of local key merging, with similar local reduce function if not combiner, then all the results ar

JQuery1.3.2 source code learning This source code uses the current jQuery 1.3.2 version. download time:. Click here to download A function 1 /*! 2 * jQuery JavaScript Library v1.3.2 3 * http://jquery.com/ 4 * 5 * Copyright (c) 2009 John Resig 6 * Dual licensed under the MIT and GPL licenses. 7 * http://docs.jquery.com/License 8 * 9 * Date: 17:34:21-0500 (Thu, 19 Feb 2009) 10 * Revision: 6246 11 */ 12 (function