高手教你PHP字符串截取函数使用_PHP教程-php教程-PHP中文网

高手教你PHP字符串截取函数使用_PHP教程

php中文网

发布： 2016-07-15 13:28:28

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学习php时，你可能会遇到php字符串截取问题，这里将介绍php字符串截取函数问题的解决方法，在这里拿出来和大家分享一下。php本身是一种简单而强大的语言。php语言拥有核心特性如强大的字符串和数组处理能力，同时极大的改进了对面向对象编程的支持（php5以上版本）。

通过使用标准的和可选的扩展模块，PHP应用程序可以连接MySQL或Oracle等十几种数据库、绘图、创建PDF文件和创建解析XML文件。你也可以使用C语言来写自己的PHP扩展模块。例如，在已存在的代码库中提供一个PHP的接口函数。你也可以在Windows下运行PHP，使用COM控制其它诸如Word和Excel的Windows应用程序，或者使用ODBC来连接数据库。在国内，PHP曾经和微软的ASP并驾齐驱，是大家常用的网络编程语言。

ASP3.0现在早已经被微软放弃了，不再更新，也许有人会认为：PHP应该也是个快作古的东西了吧？然而事实恰恰相反，PHP不仅在高速发展，把ASP远远抛在身后，而且渐渐成为现在互联网上使用最为广泛、最热门的语言。下面我们就一起利用PHP这门强大的语言解决这个问题吧。

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PHP字符串截取函数代码：

<OL class=dp-xml><LI class=alt><SPAN><SPAN class=tag><?</SPAN><SPAN class=tag-name>php</SPAN><SPAN> </SPAN></SPAN><LI class=""><SPAN> </SPAN><LI class=alt><SPAN>functionget_substr($string,$</SPAN><SPAN class=attribute>start</SPAN><SPAN>=</SPAN><SPAN class=attribute-value>'0'</SPAN><SPAN>,$</SPAN><SPAN class=attribute>length</SPAN><SPAN>=</SPAN><SPAN class=attribute-value>''</SPAN><SPAN>)  </SPAN></SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute>start</SPAN><SPAN>=(int)$start;  </SPAN></SPAN><LI class=""><SPAN>$</SPAN><SPAN class=attribute>length</SPAN><SPAN>=(int)$length;  </SPAN></SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute>i</SPAN><SPAN>=</SPAN><SPAN class=attribute-value>0</SPAN><SPAN>;  </SPAN></SPAN><LI class=""><SPAN>if(!$string)  </SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>return;  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>if($start</SPAN><SPAN class=tag>></SPAN><SPAN>=0)  </SPAN></SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>while($i</SPAN><SPAN class=tag><</SPAN><SPAN>$start)  </SPAN></SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>if(ord($string[$i])</SPAN><SPAN class=tag>></SPAN><SPAN>127)  </SPAN></SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>$</SPAN><SPAN class=attribute>i</SPAN><SPAN>=$i+2;  </SPAN></SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>else  </SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>$i++;  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute>start</SPAN><SPAN>=$i;  </SPAN></SPAN><LI class=""><SPAN>if($</SPAN><SPAN class=attribute>length</SPAN><SPAN>=='')  </SPAN></SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>returnsubstr($string,$start);  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>elseif($length</SPAN><SPAN class=tag>></SPAN><SPAN>0)  </SPAN></SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>$</SPAN><SPAN class=attribute>end</SPAN><SPAN>=$start+$length;  </SPAN></SPAN><LI class=alt><SPAN>while($i</SPAN><SPAN class=tag><</SPAN><SPAN>$end)  </SPAN></SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>if(ord($string[$i])</SPAN><SPAN class=tag>></SPAN><SPAN>127)  </SPAN></SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute>i</SPAN><SPAN>=$i+2;  </SPAN></SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN>else  </SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>$i++;  </SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>if($end!=$i-1)  </SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>$</SPAN><SPAN class=attribute>end</SPAN><SPAN>=$i;  </SPAN></SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>else  </SPAN><LI class=alt><SPAN>{  </SPAN><LI class=""><SPAN>$end--;  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>$</SPAN><SPAN class=attribute>length</SPAN><SPAN>=$end-$start;  </SPAN></SPAN><LI class=alt><SPAN>returnsubstr($string,$start,$length);  </SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN>elseif($</SPAN><SPAN class=attribute>length</SPAN><SPAN>==0)  </SPAN></SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>return;  </SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN>else  </SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute>length</SPAN><SPAN>=</SPAN><SPAN class=attribute-value>strlen</SPAN><SPAN>($string)-abs($length)-$start;  </SPAN></SPAN><LI class=""><SPAN>returnget_substr($string,$start,$length);  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN>else  </SPAN><LI class=""><SPAN>{  </SPAN><LI class=alt><SPAN>$</SPAN><SPAN class=attribute>start</SPAN><SPAN>=</SPAN><SPAN class=attribute-value>strlen</SPAN><SPAN>($string)-abs($start);  </SPAN></SPAN><LI class=""><SPAN>returnget_substr($string,$start,$length);  </SPAN><LI class=alt><SPAN>}  </SPAN><LI class=""><SPAN>}  </SPAN><LI class=alt><SPAN> </SPAN><LI class=""><SPAN></SPAN><SPAN class=tag>?></SPAN><SPAN> </SPAN></SPAN></LI></OL>

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