Seven embedded language PHP application skills_PHP tutorial

PHP (Hypertext Preprocessor) is an HTML embedded language and is currently 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.

The following are some tips I have summarized when using PHP to build a website, and I will share them with you.

1. Determine whether a function is supported

Since in PHP we can flexibly increase or decrease the modules supported by php, sometimes we Before using PHP, you will always first determine whether a module is loaded. For example, to see if the GD graphics module is supported, you can use the following code:

<ol class="dp-c">
<li class="alt"><span><span class="keyword">if</span><span>(!function_exists(</span><span class="string">"imagecreate"</span><span>))   </span></span></li>
<li><span>?> </span></li>
</ol>

In the same way, we can Use similar 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 often appear in the submission description text, such as personal It would be very pleasant if homepage and other information were automatically converted into hyperlinks when displayed, just like hyperlinks automatically appear when editing documents with WORD. The following code implements its function very well.

<ol class="dp-c">
<li class="alt"><span><span class="vars">$string</span><span> = </span><span class="string">"连接赛迪网 站点"</span><span>;  </span></span></li>
<li>
<span class="comment">//注：连接后需要有个空格或回车。 </span><span> </span>
</li>
<li class="alt">
<span class="vars">$string</span><span> = </span><span class="func">eregi_replace</span><span>(</span><span class="string">"http://([^ ,rn]*)"</span><span>,</span><span class="string">"＜a href= tarrget=_blank＞＜/a＞"</span><span>,</span><span class="vars">$string</span><span>);  </span>
</li>
<li>
<span class="vars">$string</span><span> = </span><span class="func">eregi_replace</span><span>(</span><span class="string">"ftp://([^ ,rn]*)"</span><span>,</span><span class="string">"＜a href= target=_blank＞＜/a＞"</span><span>,</span><span class="vars">$string</span><span>);  </span>
</li>
<li class="alt">
<span>print </span><span class="vars">$string</span><span>;  </span>
</li>
<li><span>?> </span></li>
</ol><br> 

3. Use PHP to process multiple checkboxes with the same name

If there are multiple checkboxes with the same name in a form, they will not work when submitted to PHP. There is only one value, not a series of values ​​separated by commas like asp. 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 is also suitable for processing multiple selections in drop-down boxes. question.

4. Use static to realize the interlaced color display of the table

We use PHP to query data from the database and output the results to the browser. If the results have many rows , if the bgcolor (background color) of the table is all monochrome, the viewer will feel uncomfortable. So how to make the colors of each row of the table different? Please look at the following code:

<ol class="dp-c">
<li class="alt"><span><span class="keyword">function</span><span> getcolor()  </span></span></li>
<li><span>{  </span></li>
<li class="alt">
<span class="keyword">static</span><span> </span><span class="vars">$colorvalue</span><span>;</span><span class="comment">//定义一个静态变量 </span><span> </span>
</li>
<li>
<span class="keyword">if</span><span>(</span><span class="vars">$colorvalue</span><span>==</span><span class="string">"#eeeeee"</span><span>)  </span>
</li>
<li class="alt">
<span class="vars">$colorvalue</span><span>=</span><span class="string">"#F5F5F5"</span><span>;  </span>
</li>
<li>
<span class="keyword">else</span><span> </span><span class="vars">$colorvalue</span><span>=</span><span class="string">"#eeeeee"</span><span>;  </span>
</li>
<li class="alt">
<span class="keyword">return</span><span>(</span><span class="vars">$colorvalue</span><span>);  </span>
</li>
<li><span>}  </span></li>
<li class="alt">
<span>print(</span><span class="string">"＜table border=1＞n"</span><span>);</span><span class="comment">//下面输出10行 </span><span> </span>
</li>
<li>
<span class="keyword">for</span><span>(</span><span class="vars">$i</span><span>=0;</span><span class="vars">$i</span><span><span class="vars">$i</span><span>++)  </span></span>
</li>
<li class="alt"><span>{  </span></li>
<li>
<span class="vars">$bcolor</span><span>=getcolor();</span><span class="comment">//换背景颜色 </span><span> </span>
</li>
<li class="alt">
<span>print(</span><span class="string">"＜tr bgcolor=$bcolor＞n"</span><span>);  </span>
</li>
<li>
<span>print(</span><span class="string">"＜td＞$i＜/td＞n"</span><span>);  </span>
</li>
<li class="alt">
<span>print(</span><span class="string">"＜/tr＞"</span><span>);  </span>
</li>
<li><span>}  </span></li>
<li class="alt">
<span>print(</span><span class="string">"＜/table＞n"</span><span>);  </span>
</li>
<li><span>?> </span></li>
</ol>

Explanation:

A static variable static $colorvalue is defined in this program, which means that after the function call ends, this variable $colorvalue still retains its value, no 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. Ways to avoid repeated references in php

As we all know, in C language, we can use #define to define a MACRO name by checking whether The MACRO name is defined to determine whether the header file is referenced. There is the same problem in PHP, for example: A refers to B, C, B refers to C. If no measures are taken, C will be quoted 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. It’s just that I recommend using the naming rules of ["user_packages"] ["headfilename"] for this global variable.

<ol class="dp-c">
<li class="alt"><span><span class="keyword">if</span><span> (!</span><span class="func">empty</span><span class="keyword">empty</span><span>(</span><span class="vars">$GLOBALS</span><span>[</span><span class="string">"FOODTAILS"</span><span>][</span><span class="string">"GLOBALDEFINE"</span><span>])) </span><span class="keyword">return</span><span>;  </span></span></li>
<li>
<span class="vars">$GLOBALS</span><span>[</span><span class="string">"FOODTAILS"</span><span>][</span><span class="string">"GLOBALDEFINE"</span><span>] = true;  </span>
</li>
<li class="alt">
<span class="keyword">class</span><span> FOODTAILS ;  </span>
</li>
<li><span>?> </span></li>
</ol>

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 are building websites, we often worry about some spam articles. Sometimes, due to network conditions and other reasons, users do not know whether the submission is successful and will submit the same form again, which results in repeated submission of the form. There is an easy way to avoid duplicate submissions 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.

<ol class="dp-c">
<li class="alt"><span><span class="keyword">if</span><span>(</span><span class="vars">$lastAction</span><span>></span><span class="vars">$userLastAction</span><span>){  </span></span></li>
<li>
<span class="vars">$userLastAction</span><span>++; </span><span class="comment">// 序列号加1 </span><span> </span>
</li>
<li class="alt">
<span class="comment">// 处理表单数据 </span><span> </span>
</li>
<li><span>}  </span></li>
<li class="alt"><span>?> </span></li>
</ol>

The main principle of this technique is that the user is not allowed to resubmit after reverting. That is to say, modifying and resubmitting after reverting is not allowed, but Ctrl-C/Ctrl-V cannot be avoided. Irrigation method.

7. Backfill the number of downloads of downloaded files

When we download software, we often see the download statistics of this software, and these statistics are provided to website management The popularity of employee analysis software brings convenience. 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 implementation code below:

a. First create a data table download (use MySql for the backend)

The download table contains the following two fields:

id Download The unique identifier of the file

downnum download times, the default value is 0

b. Implementation

assumes it has been taken out from the database: describe the file name Wubi font; download file name ：wbzx.zip; The identification number id value is 2

The generated hyperlink code after processing is:

Wubi font

下面的代码download.php处理下载次数累计及根据传递的文件名定位下载文件。

<ol class="dp-c">
<li class="alt"><span><span class="comment">//连接Mysql数据库代码略 </span><span> </span></span></li>
<li>
<span class="vars">$res</span><span>=mysql_query(</span><span class="string">"update download set downnum=(downnum+1) where id="</span><span class="vars">$id</span><span class="string">""</span><span> ,</span><span class="vars">$db</span><span>);  </span>
</li>
<li class="alt">
<span>header(</span><span class="string">"location:$filename"</span><span>);  </span>
</li>
<li><span>?> </span></li>
</ol>

http://www.bkjia.com/PHPjc/445806.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/445806.htmlTechArticlePHP (Hypertext Preprocessor)是一种 HTML 内嵌式的语言，也是目前比较流行的网页编程语言。它支持的后端数据库种类凡多，几乎含盖了当前的所有...