Seven PHP Application Tips_PHP Tutorial

PHP (Hypertext Preprocessor) is an HTML embedded language and a popular web programming language. It supports a wide variety of back-end databases, covering almost all current database systems. At the same time, it includes functions such as mathematical operations, time processing, file system, string processing, and itinerary processing that are common in general languages. In addition, it is a free system, making the cost-benefit ratio almost infinite. Below are some tips I have summarized when using PHP to build a website, and I will share them with you. 1. Determine whether a certain function is supported. Since in PHP we can flexibly increase or decrease the modules supported by PHP, sometimes we always first determine whether a certain module is loaded before using PHP, for example, To see if the GD graphics module is supported, you can use the following code: if(!function_exists(imagecreate)) { die (This host does not currently support the GD graphics module); } ?> For the same reason, we can use something like Code to test whether MSSQL, OCI and other modules are supported. 2. Change the URL in the string to a hyperlink. When submitting a form on a web page, some URLs, such as personal homepage and other information, often appear in the submission description text. If it is automatically converted into a hyperlink when displayed, it will It is a very pleasant thing, just like a hyperlink automatically appears when editing a document with WORD. The following code implements its function very well. $string = "Connect to Ccidnet http://www.ccidnet.com site"; //Note: There needs to be a space or a carriage return after the connection. $string = eregi_replace("http://([^ ,rn]*)","＜a href=DownloadFilesa2004-11-01DownloadFilesa2004-11-01{CONTENT} tarrget=_blank＞{CONTENT}＜/a＞", $string); $string = eregi_replace("ftp://([^ ,rn]*)","＜a href=DownloadFilesa2004-11-01DownloadFilesa2004-11-01{CONTENT} target=_blank＞{CONTENT}＜/ a＞",$string); print $string; ?> 3. Use PHP to process multiple check boxes with the same name. If there are multiple check boxes with the same name in a form, there will only be one value when submitted to PHP, but not Like asp, it is a series of values ​​separated by commas. The solution is to use arrays. Add [] after the name of the check box, for example: Change to:. This way php will get an array called pp. In the submitted form, first use Count(pp) to determine the number of arrays, that is, the number of selected items, and then process the arrays separately. The same principle applies to handling multiple selection problems in drop-down boxes. 4. Use static to realize the color display of the table in alternate rows. We use PHP to query the data from the database and output the results to the browser. If the result has many rows and the bgcolor (background color) of the table is all monochrome, the viewer will Not feeling very well. So how to make the colors of each row of the table different? Please look at the following code: function getcolor() { static $colorvalue;//Define a static variable if($colorvalue=="#eeeeee") $colorvalue="#F5F5F5"; else $colorvalue="#eeeeee"; return( $colorvalue); } print("＜table border=1＞n");//Output 10 lines below for($i=0;$i Note: This program defines a static variable static $colorvalue meaning After the function call ends, the variable $colorvalue still retains its value and does not disappear. When the getcolor() function is called again, the value of the variable $colorvalue is the value of $colorvalue at the end of the last function call. 5. Avoid this in PHP. As we all know, in C language, we can use #define to define a MACRO name and determine whether the header file is referenced by checking whether the MACRO name is defined. The same problem occurs in PHP, such as: A. Reference B, C, B references C, if no measures are taken, C will be referenced twice. This may cause some strange problems. Solution: Define a global variable and solve this problem by checking whether the variable is defined. The method is very simple, similar to C. But I recommend using the naming rule of [user_packages] [headfilename] for this global variable if (!empty($GLOBALS[FOODTAILS][GLOBALDEFINE])) return; $GLOBALS[FOODTAILS][GLOBALDEFINE]. = true; class FOODTAILS {... }; ?> In addition, try to use require_once "headfiles.php"; in the main program to avoid repeated references. 6. How to avoid repeated submission of forms When we build websites, we often make some mistakes. Worrying about spamming articles. Sometimes, due to network conditions and other reasons, users will submit the same form again without knowing whether the submission is successful, which results in repeated submission of the form. There is a simple way to avoid repeated submission of the same form. . First, define a session variable to save the submission sequence number of a form. Here I define it as "$userLastAction".Then add a hidden variable to the form and set the value to $userLastAction+1:> Finally, determine whether the form has been submitted before processing the submission. if($lastAction>$userLastAction){ $userLastAction++; // Add 1 to the sequence number // Process the form data} ?> The main principle of this technique is that the user is not allowed to resubmit after going back, that is to say, modify and then submit after going back. It is also not allowed, but the Ctrl-C/Ctrl-V watering method cannot be avoided. 7. Backfill the number of downloads of downloaded files. When we download software, we often see the download statistics of the software, and these statistics make it convenient for website administrators to analyze the popularity of the software. The implementation principle is: store the unique identification and download number of the software in the back-end database. When the user downloads the software, the number of downloads of the corresponding software is first updated, that is, the number of downloads is increased by 1, and then the download is officially started on the download file. Please look at the following implementation code: a. First create a data table download (using MySql for the backend). The download table contains the following two fields: id The unique identifier of the downloaded file downnum The number of downloads, the default value is 0 b. The implementation assumes that it has been Take out from the database: description file name Wubi font; download file name: wbzx.zip; identification number id value is 2. The hyperlink code generated after processing is: The code below Wubi font download.php processes the cumulative number of downloads and transfers according to The file name locates the downloaded file. //The code for connecting to Mysql database is slightly $res=mysql_query("update download set downnum=(downnum+1) where id=$id" ,$db); header("location:$filename"); ?>

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