The question mark represents a weak type in C. Nullable is a new technique provided in. NET 2.0 to indicate whether a value type can be empty.
For a type, if you can either assign a value to it or assign a null reference to it (indicating that there is no value), we can say that this type can be empty.
The following describes how to use question marks:
A. The
The question mark "? "Reason
Webpage encoding conversion is the first step for parsing and processing webpages.
More and more web pages on the Internet use UTF-8 encoding, UTF-8 with 1 to 6 bytes encoded Unicode characters, contains more than 0.1 million characters, BMP part also has more than 60 thousand characters
During encoding conversion, we often need to convert to GBK encoding for subsequent pro
PHP question mark pass value question pass value page nbsp; lt; ahref quot; syodo. php? Actionadd_py amp; py lt ;? $ V [ quot; userName quot;]? Gt; quot; gt; add friends lt; a gt; accept page $ py $ _ POST [ quot; py quot;]; why can't I receive the value of py? Ask the expert for advice and pass the value through the PHP
The existing variable, which may be of a time type, may be a Unix timestamp, i.e.
$time = '2011-12-25 00:11:20';Or
$time = 1324742400.
Now I want to make a transformation of unity, that is 时间类型 , if it is, it is converted to a Unix timestamp by a strtotime($time) function, if not the same function strtotime($time) will return false .
Then I use question mark expression $time = strtotime($time) ? strtotime(
What does it mean to add a question mark after a data type in a C # entity class
Public DateTime? createtime{ set {_createtime = value;} get {return _createtime;}}
A question mark (?) in the C # syntax. An operator is a type that can be null.
explanation above:
when working with databases and other data typ
Tags: rap detail = = Multi Name mode execute add fillVS in the new lightweight database localdb, there is this, the developer will not have to install a large SQL Server, can easily test running small projects, since it is a lightweight database, it abandoned a large body, of course, will also be limited, one of which is its default collation, Using the default collation, the Chinese data added from the Web site foreground displays garbled or variable questi
The question mark is displayed in SQLPLUS. in linux, the question mark is displayed in sqlplus, as shown below: [oracle @ why-server ~] $ Sqlplus/as sysdba SQL * Plus: Release 11.2.0.1.0 Production on Wed May 15 16:20:03 2013 Copyright (c) 1982,200 9, Oracle. All rights reserved .??? : Oracle Database 11g Enterprise Ed
The existing variable $ time may be of the time type and may be a Unix timestamp, that is, $ time #039; 2011-12-2500: 11: 20 #039 ;; or $ time1324742400. now I want to make a unified conversion, that is, if it is a time type, convert it to U using the strtotime ($ time) function... the existing variable $ time may be of the time type and may be a Unix timestamp, that is
$time = '2011-12-25 00:11:20';Or
$time = 1324742400.
Now I want to make a transformation for unification, that is, if it isT
When debugging, the program reported the following errorThe reason is that after you serialize the entity into XML in C #, there is a question mark in front of it:The XML format is not the correct XML format, so the program error.The solution is to add a piece of code that hides the illegal string at the beginning of the XML, as shown in the following code:Xmlstr = System.Text.RegularExpressions.Regex.Repla
Csv export name uncommon words change question mark csv export data
In the user name column, several user names with uncommon characters are changed to "?", The Chinese names of most users are OK,
Iconv ("UTF-8", "GBK", $ username); has no effect on uncommon words before export.
Uncommon words such as "?", "?", "?", "?"
Reply to discussion (solution)
"?", "?", "?", "?" It is not uncommon to say that
[Help] phpmyadmin. The Chinese character field is changed to a question mark. Reply to discussion (solution)
It may be the encoding of the insert data. you can check whether this is the case on the cmd interface. if so, it is likely that the encoding at the time of receiving the data is inconsistent with the database encoding.
If you want to change the encoding of the page, try again.
The page is UTF-8 ..
In fact, it is very easy to set chart indexes in INF.
The yellow question mark must indicate that you entered it in this way.
Hkr, icon, "-18"
Change the PCI device to-5.
The value is as follows:
Computer 0Display 2Mouse 5Keyboard 6FDC 9HDC 9Ports 10NET 15System 0Sound 8Printer 14Monitor 2Network Transport 3Network client 16Network Service 17
If you still have any questions, you can see the value in your
The use of free products has the obligation to promote it, so when using the tool, will automatically display a Help icon, click it will be prompted to visit the official website and appeal for donations, you can remove the icon after paying.
Syntaxhighlighter
The official approach is beyond reproach, but if we want to cancel the seemingly unsightly icon and don't want to pay for it, what is the solution? Here are three ways I've learned:
Method One
In front of the Web page, usually add th
Add a question mark after the character that represents the duplicate, such as +?,*?,{2,3}? You can stop matching greedy patterns.
var pattern=/\w{2,3}/;
Console.log ("AAAA". Match (pattern) [0]);
/* result "AAA"; greedy mode will match as many as possible,
so it will match 3 duplicate characters
* *
var pattern2=/\w{2,3}?/;
Console.log ("AAAA". Match (PATTERN2) [0]);
* * results "AA", add a
When you use SVN, you may encounter this problem, such as the desktop of the file accidentally plus the SVN question mark, so it will look very unsightly, then how to cancel it. The method is simple:
First create a Notepad file on the desktop, and then copy the sentence into: for/r. %%a in (.) do @if exist "%%A/.SVN" rd/s/Q "%%A/.SVN", save and change the file's suffix name to bat instead of txt, the file
Problem
Using the Xshell connection Aliyun ESC Server Learning C language found all the Chinese into a question mark, initially diagnosed as a character set problem. Solution
The Windows Control Panel under the language remove the English Input method solution, the completion of the screenshot below.Paths: Control Panel \ Clock, language and region \ language \ Language Optionsthinking about
This situati
Reference
Website links. Question mark?
When defining a variable, you can add a question mark after the type, indicating that the variable is nullable, and that the variable is not nullable. As follows:
var s:string? = null
var s2:string = "XXX"//If the variable is assigned null, compilation does not passThe setter met
Regular Expressions-four ways to use the question mark
Original Symbol
Because there are special meanings in regular expressions, so if you want to match, you need to escape, \? There are no quantifiers
A question mark can mean repeating the previous 0 or one time, which is either not appearing or appearing once. non
Tags: chinese support. Post logs MySQL pos cas RAC ase Java Web Query, gender word Gencun is the number, 1 for male, 2 for female, take the data when the gender into Chinese characters displayed on the page, the SQL statement as follows, the result has been a problemSelect A.emp_id,a.emp_name, case when a.emp_gendar=1 then ' Male ' when a.emp_gendar=2 then ' female ' end as Emp_gendar, B.post_nameFrom T_employee_info A, T_position_info bwhere a.post_id = b.post_id; Gender in the page does not a
About GDB Debugging a core file is always a question of a bunch of question marksProblem Description: You have added-G to the compilation option, but when you view the core file, it is a bunch of question marks, using the command: Gdb-c coreSolution: Since the use of gdb-c core is not very well supported in some systems, the following two methods are recommended:
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