item when Flex is applied? The added width is 90px, so the width of the last leftmost item is 190px.We just mentioned that grow and shrink are actually twins, actually they are really like, shrink said when the total width of the item is larger than the container, in order to get the item to fill the container, each item reduces the width. But the formulas are not the same. Why? Because it doesn't matter when you add, but when you subtract, if you only calculate the shrink value given, it's lik
Originally completed on: 2015-04-27 19:28:22Provides a way to gracefully handle Android database upgrade issues directly on the code:1 packageCom.example.databaseissuetest; 2 3 ImportAndroid.content.Context; 4 ImportAndroid.database.sqlite.SQLiteDatabase; 5 ImportAndroid.database.sqlite.SQLiteOpenHelper; 6 ImportAndroid.text.TextUtils; 7 ImportAndroid.util.Log; 8 9 public class Databasehelper extendsSqliteopenhelper {Ten public static final String db_name = "Jjtest"; one-to-one static final stri
.encoding=utf-8Log4j.appender.a3.append=trueLog4j.appender.a3.maxfilesize=2mbLog4j.appender.a3.maxbackupindex=5Log4j.appender.a3.layout=org.apache.log4j.patternlayoutlog4j.appender.a3.layout.conversionpattern=%-5p%d [%t]%c{3}.%m-%m%n?
1
The configuration file hasLog4j.logger.test=debugLog4j.additivity.test.xml=falseLog4j.logger.test.xml=debug,a3In this example, the inheritance relationship is canceled by Log4j.additivity.test.xml=false, so that the XML log is onl
[Tips] to make null value processing of C # more elegant,
Reference
Http://www.codeproject.com/Articles/739772/Dynamically-Check-Nested-Values-for-IsNull-Values? Msg = 4895299 # xx4895299xx
Http://devtalk.net/csharp/chained-null-checks-and-the-maybe-monad/
Introduction
Processing of null values in C # has always been an unpleasant task. Suppose there are the following classes:
public class Union { public string Name { get; set; } } public class Dep
= Global.amplify = {publish:function (topic) {if (typeof topic!== "string") {throw NE W Error ("You must provide a valid topic to publish."); var args = slice.call (arguments, 1), topicsubscriptions,subscription,length,i = 0,ret;if (!subscriptions[topic]) {RET Urn true;} topicsubscriptions = subscriptions[topic].slice (); for (length = topicsubscriptions.length; i More specific API use, you can refer to the following 2 articles:Brief analysis of source code of AMPLIFYJS: Event distributionExten
above will be poorly readable, And the reusability will be far from enough.
The Guava Class Library provides a tool class for parameter check-Preconditions class, which can greatly simplify the pre-judgment and processing of parameters in our code, let's make it easier and more elegant to verify the input parameters of the method. Let's take a look at the Preconditions class usage example:
Preconditions () 8, "peida"-9, "peida" 8, "" 8, getPersonByPr
Python crawler tutorial-elegant HTTP library requests (2) and pythonrequests
Preface
Urllib, urllib2, urllib3, httplib, and httplib2 are HTTP-related Python modules. If you look at the Python Module name, you will find it anti-human. What's worse, these modules are very different in Python2 and Python3, if the business code needs to be compatible with both 2 and 3, writing will crash.
Fortunately, there is another amazing HTTP library called requests,
$ g_levelConfig [$ level];}}Var_dump (getNameByLeval (1 ));Var_dump (getNameByLeval (2 ));In this case, the level. config. php configuration file must be included no matter whether the getNameByLeval function is used. It is not cost-effective.
2. Include and apply FunctionsCopy codeThe Code is as follows:Function getNameByLeval ($ level ){$ Level = intval ($ level );Global $ g_levelConfig; // Add codeRequire_once 'level. config. php ';If (! Isset ($ g_levelConfig [$ level]) {Return false;} Else
Because functional programming uses a completely different way of organizing programs, programmers who are used to using imperative examples may find functional programming a little hard to learn. In this article, you will learn some examples about how to use the functional style and use JavaScript to write good and elegant code. I will discuss:Function programming concepts include anonymous functions, different methods for calling functions, and meth
separation methods, learn ing ... toLowerCase: Returns a new string after converting all characters to lowercasetoUpperCase: Returns a new string after converting all characters to uppercaseTrim: Returns a new string after removing whitespace characters from both endsReplace: Returns a new substring that replaces all of the characters in the string with its matching characterReplacefirst: Returns a new substring that replaces the first one in the string with the substring after it matchesReplac
Elegant mobile development and client development
For mobile development, in order to achieve the page HD effect, the specifications of visual drafts often follow the following two points:
1) Select the screen width and height of a mobile phone as the benchmark (for example, 375x667 of the iPhone 6 ).
2) for HD screens, in order to achieve high-definition effects, the canvas size of the visual draft will be twice that of the benchmark (for iPhone 6: T
[$level];}}Var_dump (Getnamebyleval (1));Var_dump (Getnamebyleval (2));In this case, regardless of using the Getnamebyleval function, the level.config.php configuration file should be included in, a little less cost-effective.
2. Include, apply in functionsCopy the Code code as follows:function Getnamebyleval ($level) {$level = Intval ($level);New code for global $g _levelconfig;//Require_once ' level.config.php ';if (!isset ($g _levelconfig[$level])) {return false;}else{return $g _levelconfig[$
MRO (Method Resolution order).
If none of the above is found, then the Attributeerror exception is thrown.PS. can see from above, Dot (.) Operations are expensive, very many implicit calls, with particular emphasis on performance, and in high-frequency loops, the ability to consider binding to a temporary local variable.Here's a code snippet for everyone to do their own exploration.Class C (object): def __setattr__ (self, Name, value): print "__setattr__ called:", name, value
Using Linux's basic knowledge of its pipeline is to use the output of a program or command as an input to a program or command.Less nonsense, let's look at how Python implements the UNIX pipeline style function call.#coding =utf-8class Pipe: def __init__ (Self, func): Self.func = func- def __ror__ (self, Other): return Self.func (Other) @Pipedef Add (args): return sum (args) @Pipedef incr (ARG): return arg + 1print [1, 2, 3] | add | incrThe principle is the adorner + op
of the walk does not pass, pull back the position of the *, greedy match.As for the expansion of square brackets, it is very clear that the include and exclude variables are made.The code below.#coding =utf-8def Build_expand (p): #方括号展开 ptr2include = {} Ptr2exclude = {} Ptr2next = {} len_p = Len (p) pptr = 0 while pptrExecution results are(' AA ', ' a ') False(' AA ', ' AA ') True(' AAA ', ' AA ') False(' AA ', ' * ') True(' AA ', ' A * ') True(' Ab ', '?* ') True(' AaB ', ' c*a*b ') False(' Ca
, ..., Valuen) returns the largest of a series of values.Absnumber) calculates the absolute value of the digit, and keeps the unit sin (numbers)sine function as the cos (number) cosine function asin theinverse chord function. Returns the angle in radians , the interval isbetween-pi/2 to pi/2. ACOs (number) inverse cosine function. The interval is between 0 and pi. Tan (number) tangent function Atan (number) the inverse tangent function pi () returns the Pi (pi) isnumber (value) if the value to
ObjectiveRecently maintained an old system, there is a large number of JS splicing string code, here a total of JS stitching stringJS Native string concatenationThe strings inside JavaScript can be spliced directly with +Return "The above is splicing a JS event with a tag, you can see the inside mixed with single quotation marks and double quotation marks, with relatively strenuous.Because the single and double quotation marks are combined together, you can use the JS array to separate operation
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