question mark balloon

What is the function of the question mark after the external CSS file name? css question mark What is the function of the question mark after the externally introduced CSS file name: When you look at the code on the webpage, you

What does it mean to add a question mark after the data type ?, Data Type question mark During. net development, I saw a piece of code of this type:Public double? AskLeave {get; set ;} I can't figure it out. Why do I need to add a question

. if (cls1 is Class2) { Class2 cls2 = (Class2)cls1; } else System.Console.WriteLine("Error 2!"); I usually use this method for type conversion. However, I read an article today and compared it with another method. The as operator is used for conversion, to know that as can slightly improve the performance than is. Class2 cls2 = cls1 as Class2; if (cls2!=null) System.Console.WriteLine("Ok"); else System.Console.WriteLine("Error!"); As is slightly different. It checks whether t

.";Console.WriteLine(s);} //2BFuckprivate static void SBFuck(){string fuck;fuck = "Fuck";string s;if (fuck != null){s = fuck;}else{s = "fuck not found.";}Console.WriteLine(s);} These three methods are the same on the result, and will output fuck on the screen. Of course, write an example is only the demo level, we in the actual programming time with?? Operators are often more useful and can save a lot of trouble. For example, when dealing with page querystring:? 123456789101

Today, a colleague asked me a piece of code written by a company employee who has left the company. It looks a little strange. The Code is as follows: /// Where is it? It's strange that this string STR = Req. Form [name]? Req. querystring [name]? ""; In ?? I found it hard to understand. Later I checked the information on the Internet and explained it as follows: "Single question mark-used to assign null to

When you use the mysql database to insert data, the question mark (?) appears (?) Problem, solution, mysql question mark First, the mysql database I use is 5.7.12. Problems: 1. Data insertion error. insertion failed. The following error occurs: Incorrect string value: '\ xCD \ xF5 \ xD5 \ xBC \ xBE \ xa9' for column

PHP json_decode cannot parse special question mark characters. json_decode question mark When requesting information through other interfaces, some characters may occasionally occur. if the following conditions are met, json_decode will return null. However, this situation is not generally caused by the overall enc

C #? C #?? ?: Single question mark 1. The definition data type can be empty. Can be used to assign null to data types such as Int,double,bool that cannot be directly assigned to NULL Define 2 variables such as this: int i; Default value of 0 int? II//default value NULL2. Used to determine whether the object is empty, if the object is empty, then regardless of what the object calls do not throw an

Java question mark? Operator usage * Java provides a special ternary operator that is often used to replace an if-then-else statement of a certain type.This operator is? It seems a little confused at first But once you have mastered it, use? Operators are convenient and efficient.*? The general format of operators is as follows: Expression1? Expression2: expression3 Expression1 is a Boolean expressi

Question Returns n strings and the one with the most occurrences. Analysis Save the string and sort it. Accepted code 1 /* 2 PROBLEM:hdu1004 3 AUTHER:Nicole Lam 4 MEMO:水题 5 */ 6 7 #include Question/HDU 1004 let the balloon rise

Tags: show command merriness line is consistent character SQL command data UTF8 datahave been using the tool to connect MySQL Although small problems continue to be harmless, recently done financial cloud projects, only through the server intranet access to the database, that is, only in Linux under the command line access, in the import of Chinese when the discovery has become a question mark, after the qu

(1), C # syntax of a question mark (?) Operator refers to a nullable type. The explanation above MSDN: null to numeric and Boolean types was especially useful when you were dealing with databases an d Other data types, that contain elements, is not being assigned a value. " > when working with databases and other data types that contain elements that are not assignable, null assigned to numeric type or

From:http://www.cnblogs.com/zfanlong1314/archive/2012/02/26/2390456.html(1), C # syntax of a question mark (?) Operator refers to a nullable type. The explanation above MSDN: null to numeric and Boolean types was especially useful when you were dealing with databases an d Other data types, that contain elements, is not being assigned a value. " When working with databases and other data types that contain n

(1), C # syntax of a question mark (?) operator refers to a nullable type. The explanation above MSDN: null to numeric and Boolean types was especially useful when you were dealing with databases an d Other data types, that contain elements, is not being assigned a value. " > when working with databases and other data types that contain non-assignable elements, assign null to numeric type or boolean an

Tags: CTE file data show INI file successfully trust yourself altDue to the re-installation of the Wampserver, the problems encountered before all will appear again, then today encountered in the MySQL console, in the table input Chinese data, but there is a question mark: So this is related to coding, then we go to Wampserver to find the MySQL My.ini file, and then find [MySQL], [client], [mysqld] locatio

) 0xBB) (bom[2] = = (byte) 0xBF)) { encoding = "UTF-8"; unread = n-3; } else if ((bom[0] = = (byte) 0xFE) (bom[1] = = (byte) 0xFF)) {encoding = "utf-16be"; unread = n-2; } else if ((bom[0] = = (byte) 0xFF) (bom[1] = = (byte) 0xFE)) {encoding = "utf-16le"; unread = n-2; } else {//Unicode BOM mark not found, unread all bytes encoding = Defaultenc; unread = n; }//system.out.println ("read=" + N

How can I resolve this? Only the space becomes a question mark, other Chinese or something is normal Reply to discussion (solution) This is related to your editor, the space is not a standard spaceCan youecho Base64_encode (' Your utf-8 string ');Post the results of a view I suspect that's not a normal space. This is related to your editor, the space is not a standard spaceCan youecho Base64_encode (

Binary operators with two question marks in C # View sourceprint? Using system; Using system. Collections. Generic; Using system. LINQ; Using system. text; Namespace consoleapplication1 { Class Program { Static void main (string [] ARGs) { Int? A; A = NULL; // output 3 at this time // A = 6; // output 6 at this time Int B = ?? 3; Console. Write (B ); Console. readkey (); } } } The variable definition contains a

When the mb_convert_encoding function UTF-8 is converted to gbk, the question mark of space is changed. how can this problem be solved? Only spaces are converted into question marks, and other Chinese characters are normal. Reply to discussion (solution) This is related to your editor. spaces are not standard spaces.Can youEcho base64_encode (your UTF-8 string

Binocular operators for two question marks in C # View Sourceprint? Using System; Using System.Collections.Generic; Using System.Linq; Using System.Text; Namespace ConsoleApplication1 { Class Program { static void Main (string[] args) { Int? A A = null;//Output 3 at this time A = 6;//output 6 at this time int b = a?? 3; Console.Write (b); Console.readkey (); } } } The variable definition contains a question