1、超级简单的页面缓存
如果你的工程项目不是基于 CMS 系统或框架,打造一个简单的缓存系统将会非常实在。下面的代码很简单,但是对小网站而言能切切实实解决问题。
<ol class="dp-c"> <li class="alt"><span><span><?php </span></span></span></li> <li> <span> </span><span class="comment">// define the path and name of cached file </span><span> </span> </li> <li class="alt"> <span> </span><span class="vars">$cachefile</span><span> = </span><span class="string">'cached-files/'</span><span>.</span><span class="func">date</span><span>(</span><span class="string">'M-d-Y'</span><span>).</span><span class="string">'.php'</span><span>; </span> </li> <li> <span> </span><span class="comment">// define how long we want to keep the file in seconds. I set mine to 5 hours. </span><span> </span> </li> <li class="alt"> <span> </span><span class="vars">$cachetime</span><span> = 18000; </span> </li> <li> <span> </span><span class="comment">// Check if the cached file is still fresh. If it is, serve it up and exit. </span><span> </span> </li> <li class="alt"> <span> </span><span class="keyword">if</span><span> (</span><span class="func">file_exists</span><span>(</span><span class="vars">$cachefile</span><span>) && time() - </span><span class="vars">$cachetime</span><span> <span class="func">filemtime</span><span>(</span><span class="vars">$cachefile</span><span>)) { </span></span> </li> <li> <span> </span><span class="keyword">include</span><span>(</span><span class="vars">$cachefile</span><span>); </span> </li> <li class="alt"> <span> </span><span class="func">exit</span><span>; </span> </li> <li><span> } </span></li> <li class="alt"> <span> </span><span class="comment">// if there is either no file OR the file to too old, render the page and capture the HTML. </span><span> </span> </li> <li><span> ob_start(); </span></li> <li class="alt"><span>?> </span></li> <li><span> </span></li> <li class="alt"><span> output all your html here. </span></li> <li><span> </span></li> <li class="alt"><span><?php </span></span></li> <li> <span> </span><span class="comment">// We're done! Save the cached content to a file </span><span> </span> </li> <li class="alt"> <span> </span><span class="vars">$fp</span><span> = </span><span class="func">fopen</span><span>(</span><span class="vars">$cachefile</span><span>, </span><span class="string">'w'</span><span>); </span> </li> <li> <span> fwrite(</span><span class="vars">$fp</span><span>, ob_get_contents()); </span> </li> <li class="alt"> <span> fclose(</span><span class="vars">$fp</span><span>); </span> </li> <li> <span> </span><span class="comment">// finally send browser output </span><span> </span> </li> <li class="alt"><span> ob_end_flush(); </span></li> <li><span>?> </span></li> </ol>
点击这里查看详细情况:http://wesbos.com/simple-php-page-caching-technique/
2、在 PHP 中计算距离
这是一个非常有用的距离计算函数,利用纬度和经度计算从 A 地点到 B 地点的距离。该函数可以返回英里,公里,海里三种单位类型的距离。
<ol class="dp-c"> <li class="alt"><span><span class="keyword">function</span><span> distance(</span><span class="vars">$lat1</span><span>, </span><span class="vars">$lon1</span><span>, </span><span class="vars">$lat2</span><span>, </span><span class="vars">$lon2</span><span>, </span><span class="vars">$unit</span><span>) { </span></span></li> <li><span> </span></li> <li class="alt"> <span> </span><span class="vars">$theta</span><span> = </span><span class="vars">$lon1</span><span> - </span><span class="vars">$lon2</span><span>; </span> </li> <li> <span> </span><span class="vars">$dist</span><span> = sin(</span><span class="func">deg2rad</span><span>(</span><span class="vars">$lat1</span><span>)) * sin(</span><span class="func">deg2rad</span><span>(</span><span class="vars">$lat2</span><span>)) + </span><span class="func">cos</span><span>(</span><span class="func">deg2rad</span><span>(</span><span class="vars">$lat1</span><span>)) * </span><span class="func">cos</span><span>(</span><span class="func">deg2rad</span><span>(</span><span class="vars">$lat2</span><span>)) * </span><span class="func">cos</span><span>(</span><span class="func">deg2rad</span><span>(</span><span class="vars">$theta</span><span>)); </span> </li> <li class="alt"> <span> </span><span class="vars">$dist</span><span> = </span><span class="func">acos</span><span>(</span><span class="vars">$dist</span><span>); </span> </li> <li> <span> </span><span class="vars">$dist</span><span> = rad2deg(</span><span class="vars">$dist</span><span>); </span> </li> <li class="alt"> <span> </span><span class="vars">$miles</span><span> = </span><span class="vars">$dist</span><span> * 60 * 1.1515; </span> </li> <li> <span> </span><span class="vars">$unit</span><span> = </span><span class="func">strtoupper</span><span>(</span><span class="vars">$unit</span><span>); </span> </li> <li class="alt"><span> </span></li> <li> <span> </span><span class="keyword">if</span><span> (</span><span class="vars">$unit</span><span> == </span><span class="string">"K"</span><span>) { </span> </li> <li class="alt"> <span> </span><span class="keyword">return</span><span> (</span><span class="vars">$miles</span><span> * 1.609344); </span> </li> <li> <span> } </span><span class="keyword">else</span><span> </span><span class="keyword">if</span><span> (</span><span class="vars">$unit</span><span> == </span><span class="string">"N"</span><span>) { </span> </li> <li class="alt"> <span> </span><span class="keyword">return</span><span> (</span><span class="vars">$miles</span><span> * 0.8684); </span> </li> <li> <span> } </span><span class="keyword">else</span><span> { </span> </li> <li class="alt"> <span> </span><span class="keyword">return</span><span> </span><span class="vars">$miles</span><span>; </span> </li> <li><span> } </span></li> <li class="alt"><span>} </span></li> </ol>
使用方法:
<ol class="dp-c"><li class="alt"><span><span class="func">echo</span><span> distance(32.9697, -96.80322, 29.46786, -98.53506, </span><span class="string">"k"</span><span>).</span><span class="string">" kilometers"</span><span>; </span></span></li></ol>
点击这里查看详细情况:http://www.phpsnippets.info/calculate-distances-in-php
3、将秒数转换为时间(年、月、日、小时…)
这个有用的函数能将秒数表示的事件转换为年、月、日、小时等时间格式。
<ol class="dp-c"> <li class="alt"><span><span class="keyword">function</span><span> Sec2Time(</span><span class="vars">$time</span><span>){ </span></span></li> <li> <span> </span><span class="keyword">if</span><span>(</span><span class="func">is_numeric</span><span>(</span><span class="vars">$time</span><span>)){ </span> </li> <li class="alt"> <span> </span><span class="vars">$value</span><span> = </span><span class="keyword">array</span><span>( </span> </li> <li> <span> </span><span class="string">"years"</span><span> => 0, </span><span class="string">"days"</span><span> => 0, </span><span class="string">"hours"</span><span> => 0, </span> </li> <li class="alt"> <span> </span><span class="string">"minutes"</span><span> => 0, </span><span class="string">"seconds"</span><span> => 0, </span> </li> <li><span> ); </span></li> <li class="alt"> <span> </span><span class="keyword">if</span><span>(</span><span class="vars">$time</span><span> >= 31556926){ </span> </li> <li> <span> </span><span class="vars">$value</span><span>[</span><span class="string">"years"</span><span>] = </span><span class="func">floor</span><span>(</span><span class="vars">$time</span><span>/31556926); </span> </li> <li class="alt"> <span> </span><span class="vars">$time</span><span> = (</span><span class="vars">$time</span><span>%31556926); </span> </li> <li><span> } </span></li> <li class="alt"> <span> </span><span class="keyword">if</span><span>(</span><span class="vars">$time</span><span> >= 86400){ </span> </li> <li> <span> </span><span class="vars">$value</span><span>[</span><span class="string">"days"</span><span>] = </span><span class="func">floor</span><span>(</span><span class="vars">$time</span><span>/86400); </span> </li> <li class="alt"> <span> </span><span class="vars">$time</span><span> = (</span><span class="vars">$time</span><span>%86400); </span> </li> <li><span> } </span></li> <li class="alt"> <span> </span><span class="keyword">if</span><span>(</span><span class="vars">$time</span><span> >= 3600){ </span> </li> <li> <span> </span><span class="vars">$value</span><span>[</span><span class="string">"hours"</span><span>] = </span><span class="func">floor</span><span>(</span><span class="vars">$time</span><span>/3600); </span> </li> <li class="alt"> <span> </span><span class="vars">$time</span><span> = (</span><span class="vars">$time</span><span>%3600); </span> </li> <li><span> } </span></li> <li class="alt"> <span> </span><span class="keyword">if</span><span>(</span><span class="vars">$time</span><span> >= 60){ </span> </li> <li> <span> </span><span class="vars">$value</span><span>[</span><span class="string">"minutes"</span><span>] = </span><span class="func">floor</span><span>(</span><span class="vars">$time</span><span>/60); </span> </li> <li class="alt"> <span> </span><span class="vars">$time</span><span> = (</span><span class="vars">$time</span><span>%60); </span> </li> <li><span> } </span></li> <li class="alt"> <span> </span><span class="vars">$value</span><span>[</span><span class="string">"seconds"</span><span>] = </span><span class="func">floor</span><span>(</span><span class="vars">$time</span><span>); </span> </li> <li> <span> </span><span class="keyword">return</span><span> (</span><span class="keyword">array</span><span>) </span><span class="vars">$value</span><span>; </span> </li> <li class="alt"> <span> }</span><span class="keyword">else</span><span>{ </span> </li> <li> <span> </span><span class="keyword">return</span><span> (bool) FALSE; </span> </li> <li class="alt"><span> } </span></li> <li><span>} </span></li> </ol>
点击这里查看详细情况:http://ckorp.net/sec2time.php
1

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

推荐适合地理信息科学专业学生用的电脑1.推荐2.地理信息科学专业学生需要处理大量的地理数据和进行复杂的地理信息分析,因此需要一台性能较强的电脑。一台配置高的电脑可以提供更快的处理速度和更大的存储空间,能够更好地满足专业需求。3.推荐选择一台配备高性能处理器和大容量内存的电脑,这样可以提高数据处理和分析的效率。此外,选择一台具备较大存储空间和高分辨率显示屏的电脑也能更好地展示地理数据和结果。另外,考虑到地理信息科学专业学生可能需要进行地理信息系统(GIS)软件的开发和编程,选择一台支持较好的图形处

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。


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