php tutorial file caching example code
Cache is widely used in actual use, which can reduce access to the server database tutorial and improve running speed. Currently, caching mechanisms are frequently used in many CMS content management systems to improve the efficiency of system operation.
cache.php code is as follows:
php code
/*
Users need to define it in advance Constants:
_cachepath_ Template cache path
_cacheenable_ Whether the automatic caching mechanism is turned on, undefined or empty, indicating that the automatic caching mechanism is turned off
_recachetime_ Automatic re-caching interval, in seconds, undefined or empty, Indicates turning off automatic recaching
*/
class cache {
var $cachefile;
var $cachefilevar; //Generate the cache group file name $this->cachefilevar and file name $this->cachefile of the current page
//The cache files corresponding to different parameters of the dynamic page are also different, but all caches of each dynamic page The files all have the same file name, but have different extensions
$s=array(".","/");$r=array("_","");
$this-> cachefilevar=str_replace($s,$r,$_server["script_name"])."_".$_get[_actionvar_];
$this->cachefile=$this->cachefilevar.".". md5($_server["request_uri"]);
}
//Delete the cache of the current page/module
function delete() {
//Delete the cache of the current page
$d = dir(_cachepath_); = $d->read())) {
If (substr($entry,0,$strlen)==$this->cachefilevar) {
If (!unlink(_cachepath_."/" .$entry)) {echo "cache directory cannot be written";exit;}
>function check() {
$var =@file(_cachepath_."/".$this->cachefilevar);$var=$var[0];
)-$var>_recachetime_) {
cache
$file=_cachepath_ ."/".$this->cachefile;
//Determine whether the cache of the current page exists and whether the cache function is enabled
return (file_exists($file) and _cacheenable_ and !$ischange);
}
//Read cache
function read() {
//Return the cache of the current page
$file=_cachepath_."/".$this->cachefile;
>}
//Generate cache
function write($output) {
;
$file,'w');
//If the cache update interval is set_recachetime_
$file=_cachepath_."/".$this ->cachefilevar;
$fp=@fopen($file,'w'); ;}
Usage process:
php code
define("_cachepath_","./cache/");
define("_cacheenable_","1");
define("_recachetime_","43200");
include('cache.php');
$cache=new cache();
if ($cache->check()) {
$template=$cache->read (); Page content. . . .
$template = ob_get_contents();
$cache->write($template);
} }
?>

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。

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。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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