B = "a" + "true";System.out.println ((A = = b)); result = TrueString a = "a3.4";String B = "a" + 3.4;System.out.println ((A = = b)); result = TrueAnalysis: JVM for string constant "+" number connection, the program compile period, the JVM will be the constant string "+" connection optimization to the concatenated value, take "a" + 1, the compiler is optimized in class is already A1. The value of its string constants is determined at compile time, so the final result of the above program is true
Today's content:Knowledge Point one: RegularWhat is a regular:is to use a series of characters with special meanings to form a set of rules that are used to describe a character string.The regular is used to remove a small string of rules in a large string.Why use the Regular:1. User Registration2. Crawler programsHow to use:Re.findallRe.findall module:\w letters, numbers, underscoresPrint (Re.findall (' \w ', ' yangzz:age_18 '))\w no letters, numbers, underscoresPrint (Re.findall (' \w ', ' yan
reference "value" (that is, the memory address), which forces the reference to point only to the object that was initially pointed to, and changes its point to cause a compile-time error.Final is not responsible for the change in the object it points to. several examples of string constant pool problems Here are a few common examples of comparative analysis and understanding:String A = "A1";String B = "a" + 1;System.out.println ((a = = b));//result = TrueString a = "atrue";String B = "a" + "tru
PHP does not seem to be the same as the ASP "/" to represent the root directory, replaced by $_server[' Document_root ', others are the same: ... /represents an upward layer./represents the current layer. If a/b/c/s.php now wants to invoke the/bb/s2.txt under the root directory, then:
$RootDir = $_server[' Document_root '];$fireDir = "$RootDir/bb/s2.txt";
Or: ". /.. /.. /
: JVM for string constant "+" connection, the program compile period, the JVM will be the constant string of "+" connection optimization to the value after the connection, take "a" + 1, after the compiler optimization in class is already A1. The value of the string constant at compile time is determined, so the final result of the above program is true.
Example 4:
Java code
String a = "AB";
String BB = "B";
String B = "a" +
First, awk uses ordinary variables in the shell
Method 1: Use the quotation mark method
Aa= "Hello"
awk ' BEGIN {print ' $aa '} '
Output $AA
awk ' BEGIN {print ' $aa '} '
Output Hello
awk ' BEGIN {print ' ' $aa '} '
Output empty
Aa= "hello! Coder "
awk ' BEGIN {print ' $aa '} '
Error, double quotes do not match, because space appears in the middle
awk ' BEGIN {print ' ' $aa ' '} '
Hello! can be displayed normally Coder
Method 2: Using the-V method
Awk-v varaa= "$aa" ' BEGIN {print Varaa}
assign it to the string variable S2. Judge S1+s2= "A" in the character table, then s1=s1+s2= "a" (see table 2, second row).
4) Read the next character a in the image data stream and assign it to the string variable S2. Judge S1+s2= "AA" is not in the string table, output s1= "a" in the word list of index 0H, and at the end of the string table for s1+s2= "AA" to add index 4H, and s1=s2= "a" (see table 2, the third row).
5) Read the next character B assigned to S2. Judge S1+s2= "AB" is not in the
= "A1";
String B = "a" + 1;
System.out.println ((A = = b)); result = True
String a = "atrue";
String B = "a" + "true";
System.out.println ((A = = b)); result = True
String a = "a3.4";
String B = "a" + 3.4;
System.out.println ((A = = b)); result = True
Analysis: JVM for string constant "+" number connection, the program compile period, the JVM will be the constant string "+" connection optimization to the concatenated value, take "a" + 1, the compiler is optimized in class is already A1. The val
Some may ask questions like this. the expected result of the table's data in the following example is idaabb201734562506643898920.00002. of course, the environment is SQL Server's answer and analysis as follows: 1, many friends often ask questions similar to this,
The data in the table is as follows:
ID AA BB
1 123 456
1 4535 54
1 60 6564
1 60 656
2 50 664
2 60 6
3 89
4 40 4242
The expected result is:
ID AA BB
Directly cut the topic. There is A table in the table: ChenJiID, DanWeiID, Name, and ChenJi. The IDDanWeiIDNameChenJi ---------------------------- the consumer opens two connections in the query analyzer to connect A to begintrant.
There is a table in the direct cut topic: ChenJi ID, DanWeiID, Name, in the ChenJi table, record ID DanWeiID Name ChenJi --- ----------- --------- 1 1 aa 91 2 1 bb 91 3 1 cc 33 4 2 dd 164 5 2 ee 155 6 2 ff 166 in the query
This post was last edited by Zhoumengkang on 2013-09-12 10:03:14
Prior to the introduction of jquery
var str = "{' A ': ' B ', ' AA ': ' BB '}", var str2 = eval (' (' +str+ ') '), var type = typeof (STR2); Console.log (str); Console.log (type) ;//objectconsole.log (str2); $.post ('./bb.php ', {' Data ': str2});
Bb.php's Code
$data = $_post[' data '];var_dump ($data);
The console looks at the returned results, and the output is directly an array.
. Out. println (A = B ));// Result = true
String A ="Atrue";
String B =""+"True";
System. Out. println (A = B ));// Result = true
String A ="A3.4";
String B =""+3.4;
System. Out. println (A = B ));// Result = true
Analysis: JVM connects the "+" Number of string constants. During the program compilation period, the JVM optimizes the "+" connection of the constant string to the connected value, take "A" + 1 as an example. After the compiler is optimized, it is already A1
= "A1"; string B = "A" + 1; system. out. println (A = B); // result = true string a = "atrue"; string B = "A" + "true"; system. out. println (A = B); // result = true string a = "a3.4"; string B = "A" + 3.4; system. out. println (A = B); // result = true analysis: JVM connects the "+" Number of string constants to compile the program, the JVM optimizes the "+" connection of the constant string to the connected value. Take "A" + 1 as an example. After the compiler is optimized, it is already A1
; end if;end if;if (@weather is not null) thenb:beginset current_gini = (select min(gini) from finalgini where statetemp=1);set current_class = (select parent from finalgini where gini = current_gini);drop table if exists aa;create temporary table aa (namee varchar(100));insert into aa select class from finalgini where parent=current_class;insert into aa select class2 from finalgini where parent=current_class;tt:while (1=1) doset @x = (select namee from aa limit 0,1);if (@x is not null) thena0:b
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Executes one or more statements for each attribute of an object, or each element in an array or set.
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For ([Var] variable in {object | array | collection })
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tcp_wrappers = YES // tcp_wrappers is set to yes, the ftp server uses tcp_wrappes as the host access control mode. Tcp_wrappers can implement host address-Based Access Control for network services in linux systems, and hosts in the "/etc" directory. allow and host. two deny files are used to set tcp_wrappers access control, hosts. the allow file settings allow access records, host. deny File Settings deny access records.
Start the vsftpd Server# Service vsftpd startStarting vsftpd for vsftpd: [
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