explain gigabytes

I don't understand why output 4. Can someone help me explain it? Thank you. -- Linux general technology-Linux programming and kernel information. The following is a detailed description. # Include Func (char * str) { Printf ("% d", sizeof (str); // Why is output 4 here? Printf ("% d", strlen (str )); } Int main () { Char a [] = "123456789 "; Printf ("% d", sizeof ()); Printf ("% d", strlen ()); Func (); Return

. Because "top 1" means to extract the first record, it should be used if you want to guess the second record:Select top 1 len (column name) from Table NameWhere column name not in (select top 1 column name from table name)2. ASCII code analysis method to guess the user and passwordASC () and Mid FunctionsExample: mid (column name, N, 1)ASC (mdi (column name, N, 1) obtains the nth ASCII code of the "column name ".The explain statement is:And (select t

easier to understand, we will explain it through a simple example below. Consider this example. Suppose there is an abstract concept about the door in our problem field. The door has two actions: open and close, in this case, abstract class or interface can be used to define a type that represents the abstract concept. The definitions are as follows: Use abstract class to define door: Abstract class door {Abstract void open ();Abstract void

During a query optimization process, you need to constantly use the explain statement to verify the effectiveness of various adjustments. The MySQL explain function displays the following information: ID: The serial number queried in the execution plan selected by MySQL query optimizer. Select_type: the query type used, mainly including the following query types. Dependent subquery: The first

When writing software documents, you can use the dr. Explain tool to get twice the result with half the effort.Document tool dr. Explain features Automatically capture and identify interface elements Export CHM, PDF, HTML, and rtf formats Ø keywords can be added to files in chm format to form an index list Various interfaces and sub-elements such as Web winforms FLEX can be obtained.One-click capture In

Explain basic SQL syntax and SQL syntax 1. Create a database Create database Name 2. delete a database Drop database name 3. Back up SQL server The device that creates the backup data Use master Exec sp_addumpdevice 'name', 'new name', 'path' Start backup Backup database pubs to new name 4. Create a table Create table Name (column name 1, column name 2) 5. Create a new table based on an existing table Create table new table name like old table name Cr

Why is the result below? could you please help me explain it? Why is the result below? could you please help me explain it?Bool (true)Int (8) Reply to discussion (solution)$ A is assigned 6 amp; $ B = 7The original formula is equivalent to $ a = (6 $ B = 7)Because (6 $ B = 7) is true, bool (true) is returned)Because the condition is true, $ B ++ takes effect and $ B is 8 at last. $ A = 4; $ B = 5; if

Please help to explain, multi-linked check, I do not understand, thank you SQL Code Please help to explain, multi-linked check, I do not understand, thank you ------Solution-------------------- SQL code select * FROM (select Bookid,count (BookID) A s degree from Tb_borrow Group by BookID) as Borr join (select B.*,c.name as Bookcasename,p.pubname,t.typ Ename from Tb_bookinfo B l

Linq --- I'll explain the order for you. Your beauty is not only a query statement, but also a write by using This is a group of extensions for the c # and Visual Basic languages. It allows you to write C # Or Visual Basic code to query memory data in the same way as a database. LINQ is short for Language Integrated Query. Translation into Chinese is Language Integrated Query, which is a feature Integrated in. NET programming Language. It has become a

Explain the SQL syntax example of the most efficient paging query in ORACLE, oraclesql -- 1: no order by statement. (Most efficient) -- (After testing, this method has the lowest cost. Only one layer is nested, and the speed is the fastest! Even if the queried data volume is large, it is almost unaffected and the speed is still high !) SELECT * FROM (select rownum as rowno, t .* FROM emp t WHERE hire_date BETWEEN TO_DATE ('20140901', 'yyyymmdd ') AND

Node. js entry-create a project and explain it in detail. node. js entry-level After thinking for a long time, I always want to write something that is helpful to everyone. Today I will explain how to generate a project. At present, the market generally requires a full stack of people ----- mean (mongo, express, angular, nodejs), which can be developed from the front end to the backend and the database. It

Description: bitsCN.com Description You can use the explain command to understand how mysql processes statements and analyze the performance bottleneck of queries or table structures. Through expalin, we can get: 1. reading sequence of the table 2. read operation type of the table 3. which indexes can be used? 4. which indexes are actually used? 5. Reference between tables 6. The Optimizer queries the number of rows in each table.

Explainmysql query statement MySQLexplain BitsCN.com Explain mysql Query statement Description: SQL code Mysql> explain SELECT 'content _ id', 'content _ old_id ', 'content _ hasimg', 'content _ time_update ', 'content _ title_long', 'vhost _ content '. 'site _ id', 'site _ domain ', 'site _ name ', 'site _ state' FROM 'vhost _ content' left join 'vhost _ site' ON 'vhost _ content '. 'site _ id' = 'vhos

For reference, who can explain the following code snippet 1: $ array_a = nbsp; array ( nbsp; 0 nbsp ;= gt; nbsp; 'A' nbsp;); $ array_ B = nbsp; amp; $ array_a; $ array_c = nbsp; who can explain this situation? Code Segment 1: $ Array_a = array (0 => 'A ');$ Array_ B = $ array_a;$ Array_c = $ array_ B;$ Array_d = $ array_ B;$ Array_c [0] = 'B ';Echo 'variable a: '; var_dump ($ array_a );Echo 'varia

Ask the seniors to help me explain what the following statement means. Thank you lt ;? Session_start (); require_once ("common/Common. inc. php "); $ AgentInfo nbsp ;= nbsp; GetAgentInfo (); $ mainTpl nbsp ;= nbsp ask the seniors to help me explain what the following statement means. thank you. session_start();require_once("common/Common.inc.php");$AgentInfo=GetAgentInfo();$mainTpl=newMySmarty();$main

Help me explain the code $ str (isset ($ _ POST [source])? $ _ POST [source] :); how to understand this sentence. What are the functions of question marks and colons. Please give me some advice. I cannot find any information. The source is from lt; textareaname quot; source quot; lt; textarea gt; --- explain the code for me. $ Str = (isset ($ _ POST ['source'])? $ _ POST ['source']: ''); How can this

ThinkPHP verification code display problems, please explain !!! This is the code: lt; p gt; verification code: lt; input nbsp; type = "text" nbsp; name = "vircode" nbsp; onkeyup = "return nbsp; login_chkcode ( ThinkPHP verification code display problem, please explain it !!! This is the code: Verification code: Then the local display is normal: And then upload it to the server: Then ff repor

: This article mainly introduces Baidu engineers to introduce the implementation principle and performance analysis of PHP functions (1). For more information about PHP tutorials, see. Baidu engineers explain the implementation principle and performance analysis of PHP functions (I) PrefaceIn any language, a function is the most basic component unit. What are the features of php functions? How is function calling implemented? What is the perform

Which expert can explain the idea of discuzX2.5uploadindex. php file! Discuz The code for discuz X2.5 upload/index. php is as follows. let's explain the running steps (architecture ideas). the more detailed the code is, the better. thank you very much !!! 'space', 'uid'=>$_SERVER['QUERY_STRING']);} else {$url = '';$domain = $_ENV = array();$jump = false;@include_once './data/sysdata/cache_domain.php';$_

Who can explain in detail the PHP $a = 10; $b = $a--+--$a; Implementation process? When I was reading Gaulo's book, "PHP," I Found $a = 10;$b = $a++ + ++$a; //书上写的执行过程是$a先自增1后再自增1，再赋给$becho $a; //$a = 12;echo $b; //$b = 22;$b = $a-- - --$a; //$a先自增1后再自增1，再赋给$becho $a; //$a = 10echo $b; //$b = 2 If it's logical, then add $b = $a-- + --$a;echo $a; //$a = 8;echo $b; //$b = 18; Can someone please tell me the detai