correct use of ampersand

157 suggestions for writing high-quality code to improve C # programs [correct string operations, use default transformation methods, but do not treat forced conversions with as and is], Preface This document describes the first three suggestions. 1. Correct string operations Suggestion 2. Use the default Transformatio

behavior }); This is also valid for form submission, you can better handle the error situation, do not expect your code to work properly, the correct response when the error is always better than the assumption that the code is not wrong. 3. In the product phase, if the function of this design JS, it should also be placed in the first line. Remember, you don't have to be the first line of a function, but the sooner the better, the princip

each input are recorded in the history and their results, the current number of attempts is 9, time 47s, but has not guessed, then the display "Unfortunately the game failed!" dialog box.And now this operation, showing "4a0b" is the success, the number of attempts to 3, time 15s, and prompted "Congratulations on your success!" ”。If you want to continue playing, click "Restart" and you can play again.All in all, this game is relatively simple, involving MFC's menu bar, toolbars, dialog boxes, te

Java Theory and Practice: Correct Use of Volatile variables (1) The volatile variable in Java can be seen as a "to a lesser extent"synchronized"; AndsynchronizedCompared with the block, the volatile variable requires less encoding and less runtime overhead. However, the only function it can implement issynchronized. This article introduces several effective modes for Using volatile variables, and emphasiz

, the remaining charge of 95%, the battery will be charged to 100%, this is not a charge of electricity, to such 20 times, add up completely put 100% of the electricity, full after the full cycle. So it is not correct to use the battery completely and then charge it, and it will damage the battery. Four, the voltage is not normal also can damage the computer. High or low pressure can damage the batt

When you register on a forum, there is usually an e-mail address verification function, when you enter an illegal format, there will be some kind of error message. We can use the following rule expressionEreg ("^[a-za-z0-9_] @[a-za-z0-9-]. [ a-za-z0-9-.] $] ", $email); But the function of the above equation is to check only strings and not output. We can further use this formula to achieve the function of r

If you have any questions please contact me: http://www.webjx.com web@webjx.comReprint please indicate the source When you register on a forum, there is usually an e-mail address verification function, when you enter an illegal format, there will be some kind of error message. We can use the following rule expression Ereg ("^[a-za-z0-9_]+@[a-za-z0-9\-]+\.[ A-za-z0-9\-\.] +$] ", $email); But the function of the above equation is to check only string

status (readable ): $ cp chpasswd /var/www/ Or, if you apply the Lighttpd web server: $ cp chpasswd /home/lighttpd Step 2: execute the command as root through sudo After the Apache or Lighttpd web server enters the background for running, it will immediately apply non-root permissions. This can prevent password modification, just as the passwd command requires the root permission to correct the passwords of other user accounts. Generally, Apache 2

In the oracle database, the correct use of the connection detection statement in the application is blog. csdn. netmsdnchinaarticledetails000013765 in many programs, connection detection (or connection detection) Statements use selectsysdatefromdual. This is a typical "as long as the function is implemented, no matter what the performance is. Actually In the orac

Dagger2 Use the correct posture. The previous article "[Dagger2 This introduction will not have to give up]" (http://blog.csdn.net/u012943767/article/details/51897247 "introduced some of the Dagger2 of some shallow use, I think it is very suitable for the introduction of the Dagger2 of the silly explanation, and later found that some of the content is not caref

program behavior to be unknown. The reason is that map is an associative container, and if an element has been deleted, the corresponding iterator is invalidated and should not be used again, otherwise it will result in undefined behavior of the program.You can solve this problem in the following ways:The correct wording1. Locate the next element using the iterator that was previously removed. How STL recommendations are used1 for (ITER iter=maptest

To determine the amount of input is the correct amount of methods there are two, one is a regular expression, the other is a TextField proxy method Sometimes it is inevitable to encounter such a demand, does not conform to the rules of the amount of input, it is more reasonable to use this method If you set the input keyboard to decimal pad, enter a number and a decimal point; if you set the keyboard to n

The IMG tag has two attributes: ALT and title. Many beginners are still confused about the correct use of these two attributes. Of course, this is partly due to IE browser. Correct use of these two attributes can not only improve the search capability of images, but also help in user experience. The following describes

overhead. Join conditions to fully consider the table with the index, the number of rows of tables, and pay attention to optimize the table order; The simple point is to reduce the amount of data that will be associated afterwards as early as possible.In general, SQL Server automatically optimizes connections to tables. For example:Select Name,no from AJoin B on A. id=b.idJoin C on C.id=a.idWhere Name= ' Wang 'Although the a table is listed first in from, then B, and finally C. However, SQL Ser

When the Linux server time is not correct, you can use the Ntpdate tool to correct time. Installation: Yum Install Ntpdate Ntpdate Simple usage: # ntpdate IP # ntpdate 210.72.145.44 The following are some of the available NTP server addresses: Name Ip Location 210.72.145.44 210.72.145.44 China (National Timing Center)

This article mainly introduces how to use VBS to get the previous day of the current date and correct the output format. For more information about how to obtain the current date, see method 1: Currentdate1=date()msgbox Currentdate1 Method 2: Currentdate2=year(Now)"-"Month(Now)"-"day(Now)msgbox Currentdate2 Add one: if you want to get a date that is preceded by one-digit prefix with 0, for example, 2016516

Opcodecache schematic: Common opcache extensions include apc, xcache, and eAccelerate. The following uses apc as an example: if apc is not enabled: if apc is enabled, the performance can be improved by 30% to 40%. The performance of the stat function of apc is doubled! Original article address: Correct Use of opcodecache greatly improves PHP Performance Opcode cache schematic: Common opcache extensions inc

Correct use and space occupation of NULL in SQL Server, servernull We often encounter NULL in the use or maintenance of SQL Server. What is NULL? The following is a brief description provided by MSDN (see "Null Values "): A value of NULL indicates that the value is unknown. A value of NULL is different from an empty or zero value. no two null values are equal.

,fname,lname) VALUES (2, ' Dave ', ") insert into test_null (num,fname) VALUES (3, ' Aaron ') INSERT into Test_null (num,fname) VALUES (4, ' Betty ') To verify that null values are unknown, we use the following SQL query table Test_null records to make the lname field = action: If two null can be equal, then 4 records will be output. Actually output only 2 records SELECT * from test_null tn left JOIN test_null g on tn.num = g.num

, logical read 18,984 times, physical read 0 times, read 0 times, LOB logic read 0 times, lob physical read 0 times, lob read 0 times.Table ' Workflowbase '. Scan count 3, logical read 1589 times, physical read 0 times, read 0 times, LOB logic read 0 times, lob physical read 0 times, lob read 0 times.Two IO gap:56952+1589=58,541 times (using in) 18984+1589=20573 times (using exists) Using exists is 2.8 times times the in and query performance is greatly improved. EXISTS makes queries faster be