directly to indicate the number of rows to be operated. sed '2d 'aaa.txt must be used to delete the second line in the aaa.txt file. The regular expression must be used to separate the two backslashes. sed '/^ Tom/d' aaa.txt # trim deletes the line starting with Tom in aaa.txt * if no range is specified, full text will be manipulated. sed 'd 'aaa.txt # delete all rows in aaa.txt
1. sed '$ d' aaa.txt # Delete the last row in aaa.txt (operate on a single row)2. sed '7, 9d' aaa.txt # Delete the se
The usage of Delphi tstringlist tstrings is an abstract class. In actual development, tstrings have the most applications besides the basic types.
We all know the general usage. Now we will discuss some of its advanced usage.
First, list the several attributes to be discussed:
1. commatext
2. delimiter delimitedtext
3. First read the names Values valuefromindex: commatext. How to use it? Use code to speak:
Const
Constr: String = 'aaa, BBB, CCC, DDD
match multiple times
{N ,}?
Lazy match N-multiple times
{M, n }?
Lazy Match m-N times
Quantifiers:
Posite Word Table:
Syntax
Description
? +
Occupy matching 0-1 times
++
Possession Matching 1-multiple times
* +
Possession matches 0-multiple times
{N} +
Possession matching multiple times
{N ,}+
Possession match N-multiple times
{M, n} +
Occupy M-N times
Ex
while ($i = 'AAA' $j = 'BBB') { var_dump($i, $j); sleep(3);}
输出结果bool(true)string(3) "BBB"
-------------------------------------------------------------在写一个后台监听程序的时候使用了while循环,于是纠结了一下`while`中的条件表达式
For the above code I expected output AAA BBB But why is it true BBB
Look at this piece of code.while($ret
{Code ...} {code ...} {code ...} for the above code, I expected to output AAABBB, but why is it trueBBB? READ this code {code ...} here, how does the conditional expression $ ret100 in brackets determine whether the result is true or false. What I want is to set the value 100 first...
while ($i = 'AAA' $j = 'BBB') { var_dump($i, $j); sleep(3);}
Output result bool (true) string (3) "BBB"
-------------
Here's the thing: I'm querying the MySQL database except for a record that contains variables such as {$aaa}, {$bbb},
Now I want to assign the two variables before the output, but the result of the output is the variable ....
For example:
$rs _sql =mysql_query ("Select content from table where id = ' 1 '");
$row _rs_sql = mysql_fetch_array ($rs _sql);
The Content field is: Hello {$aaa}, long time no see, I was thinking of you {$
following code:
Background-image:linear-gradient (45deg, #bbb 25%, transparent 0), linear-gradient (45deg, Transparent 75%, #bbb 0)Note: The information for linear-gradient (45deg, Transparent 75%, #bbb 0) is covered by linear-gradient (45deg, #bbb 25%, transparent 0).
Example code:
width:200px;
One, stripe background
Using background as the Linear-gradient function, the linear-gradient value is as follows:
To left right top bottom
Color: Specify color
Color-stop: Specifies the starting and ending color of the gradient
Length: Specifies the position of the starting and ending color with a value of
Percentage: Specify the position of the starting and ending colors in percent
Syntax format: linear-gradient ([[
Side-to-corner:[
Well, I really don't. Feel I write the essay is very slag, not necessarily, everybody don't be misled by me, best not to see. I try to make sure it's all right to write.First of all, these two got me dizzy.1.//Regardless of hierarchy: relative path2./Care Level: represents an absolute path to an element3.//DDD/BBB: Mixed explanation? All the DDD elements under the BBB element, no matter where4. * Indicates
A list of Python:Actually the so-called list I personally feel the same as the array in the shell (just a personal opinion oh), the list is actually a combination of elements:
Format:
Name = [A,b,c,d]
Subscript:
Each element in the list corresponds to a subscript with a starting bit of 0such as list [A,b,c,d]A corresponds to a subscript of 0The subscript for B corresponds to 1c the corresponding subscript is 2......1.1. definition list:For example, the definition list
version
$ cat /etc/lsb-releaseDISTRIB_ID=UbuntuDISTRIB_RELEASE=14.04DISTRIB_CODENAME=trustyDISTRIB_DESCRIPTION="Ubuntu 14.04.X LTS"
In this way, you can start installing BigBlueButton.Start installation: if an error occurs during installation, stop and check the command content carefully. Make sure to solve the problem before proceeding to the next step. You may have asked Google or duniang, you know. 1. Update the service
$ grep "multiverse" /etc/apt/sources.list
See a URL similar to this
d
/* Initialize the test table */--Create a test tableCREATE TABLE Testlock(AAA number NOT NULL,BBB Nvarchar2 (TEN) is not NULL,CCC Nvarchar2 (TEN) NOT NULL);Create INDEX Pk_testlock on Testlock (AAA);--Random insertion point dataINSERT into Testlock VALUES (' 1 ', ' BBB ', ' CCC ');INSERT into Testlock VALUES (' 2 ', ' BBB ', ' CCC ');INSERT in
Basic php questions for help !!!!!! This is the case: I query one record from the mysql database. This record contains variables such as {$ aaa} and {$ bbb,
Now I want to assign values to the two variables before the output, but the output result is still a variable ....
For example:
$ Rs_ SQL = mysql_query ("select content from table where id = '1 '");
$ Row_rs_ SQL = mysql_fetch_array ($ rs_ SQL );
///// The content field is: Hello, {$ aaa}. it's be
Email: longsu2010 at yeah dot netSome people sent me the following code a long time ago and asked me some questions. I simply wrote a blog to share it with you. I stated in advance that this blog only analyzes the problem and does not provide a solution (I do not know the true intention of the person who wrote the code ).
It is a headache to read the code at first glance. I will not write the code at all. The Code is as follows:
Function aaa (sColor ){This. color = sColor;If (typeof aaa. _ is _
because no value in the first read map returns NULL, and Cachemap.put (Key, "AAA") $ * is not re-assigned to object so it is nullPanax Notoginseng * solution is obtained directly from Cachemap.get (key), do not intermediate object, here I will not change - * Thread-3: AAA the * Thread-4: AAA + * Thread-5: AAA A * Thread-6: AAA the * Thread-7: AAA + * Thread-8: AAA - * Thread-9: AAA $ * $ * @paramKey - * @return - */ the //Public Object GetData (Strin
times the file was hard-linked;WJQ (1): denotes the owner of the document;WJQ (2): Represents a group of documents;25 March 12 09:26: Time when the file was last modified;Example:[Email protected] wjq]# ls-lTotal dosage 10392-rw-rw-r--. 1 wjq wjq 0 March 14:21 ADrwxrwxr-x. 4 WJQ WJQ 25 March 09:26 ABDrwxr-xr-x. 2 root root 6 March 6 22:21 BinDrwxrwxr-x. 2 WJQ WJQ 6 March 6 22:05 Boot-RW-------. 1 wjq wjq 5304320 March 4 08:22 core.3441-RW-------. 1 wjq wjq 5312512 March 2 20:30 core.95434.mkdir
the order of the winning red part, you can understand why. Because the first query returns a column that has more bytes than Max_length_for_sort_data, which causes the sort to be sorted in a regular order, in which case MySQL sorts the rowid and turns random io into sequential io, so it returns 5 in front, 6 in the back While the second query is optimized, there is no process to skim the data for the second time, and the relative position of the sorted record is maintained. For the first statem
1. Printf enumeration to display the ordinal of an enumeration:
#include int main(void) { enum ABC{AAA,BBB,CCC}; enum ABC e1,e2,e3; e1 = AAA; e2 = BBB; e3 = CCC; printf("%d, %d, %d\n", e1, e2, e3); getchar(); return 0; }
2. You can define variables at the same time when you define enumerations:
#include int main(void) { enum ABC{AAA,BBB
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