


Output Control of PHP caching mechanism, outputcontrol
-------------------------- -------------------------------------------------- ----------------------------
In the configuration of version php5.2, output_buffering is turned off by default. Running the following three lines of code will result in a warning: Warning: Cannot modify header information - headers already sent
<span>echo</span> 'hello1'<span>; </span><span>header</span>('content-type:text/html;charset=utf-8'<span>); </span><span>echo</span> 'hello2';
Two ways to enable OB cache=>
1. Enable output_buffering = 4096 in php.ini
//# If this directive is enabled, then each PHP script is equivalent to calling the ob_start() function at the beginning. PHP5.5 has output_buffering = 4096 enabled by default
2. Directly in the program ob_start();
//# Turn on output buffering. When output buffering is activated, the script will not output content (except http headers), instead the content to be output is stored in an internal buffer.
//# The contents of the internal buffer can be copied to a string variable using the ob_get_contents() function. To output the content stored in the internal buffer, you can use the ob_end_flush() function. In addition, using the ob_end_clean() function will silently discard the contents of the buffer.
<span>/**<br /> * output_buffering = off 情况下测试<br /> * @chenwei <www.chenwei.ws><br /> */<br />ob_start</span>(); <span>//</span><span>开启ob缓存</span> <span>echo</span> 'hello1'; <span>//</span><span>存入ob缓存</span> <span>header</span>('content-type:text/html;charset=utf-8');<span>//</span><span>存入程序缓存<br /><br />//ob_end_clean(); //清空ob缓存,并关闭ob缓存<br /><br /></span>
<span>echo</span> 'hello2'; <span>//</span><span>存入ob缓存</span> <span>$str</span> = <span>ob_get_contents</span>(); <span>//返回</span><span>ob缓存的数据(不清除缓冲内容)</span> <span>file_put_contents</span>('ob.txt', <span>$str</span>); <span>//</span><span>把$str保存到文件</span> <br />//ob_clean(); //清空ob缓存<br /> <span>echo</span> 'hello3'; <span>//</span><span>存入ob缓存</span> <span>echo</span> 'hello4'; <span>//</span><span>存入ob缓存<br /><br />/* 此脚本将生成ob.txt文件,存入hello1hello2,浏览器输出hello1hello2hello3hello4 */<br />/* 若ob_clean()注释打开,那么生成的ob.txt文件中将没有内容,浏览器输出hello3hello4 */<br />/* 若ob_end_clean()注释打开,那么ob.txt中依然没有内容,因为关闭了ob缓存,浏览器输出hello2hello3hello4 */<br /></span>
ob_flush() and ob_end_flush() Example:
<span>ob_start</span><span>(); </span><span>echo</span> 'abc'<span>; //存入ob缓存 </span><span>header</span>('content-type:text/html;charset=utf-8'<span>); //存入程序缓存 </span><span>echo</span> 'hello'<span>; //存入ob缓存 </span><span>ob_flush</span><span>(); //将ob缓存中的内容输出到程序缓存,清空ob缓存,不关闭ob缓存<br />//ob_end_flush() //将ob缓存中的内容输出到程序缓存,清空ob缓存,关闭ob缓存 </span><span>echo</span> 'aa'<span>; //存入ob缓存 </span><span>echo</span> <span>ob_get_contents</span>();<br /><br />/* 最后输出abchelloaaaa */<br />/* 注释ob_flush,打开ob_end_flush,最后输出abchelloaa */
----------------------------------------@黑eyedpoet
Note: When output_buffering = 4096 is turned on
ob_end_clean() only closes the ob cache once (that is, when ob_start is turned on), and the system does not close it
Same as ob_end_flush().
Operating principle/principle of OB cache=>
1. The ob cache is turned on, and the echo data is first put into the ob cache
2. If it is header information, put it directly in the program cache
3. When the page is executed to the end, the ob cached data will be placed in the program cache, and then returned to the browser at once
Finally there is a flush(); to force refresh the PHP program cache to the browser cache.
//# Feature: Some versions of Microsoft Internet Explorer will only start displaying the page after receiving 256 bytes, so some extra spaces must be sent to allow these browsers to display the page content.
<span>echo</span> <span>str_repeat</span>('', 1024);<span>//</span><span>重复输出多个字符(解决浏览器缓存256字节之后再输出的情况)</span> <span>for</span>(<span>$i</span>=0; <span>$i</span> < 5; <span>$i</span>++<span>) { </span><span>echo</span> <span>$i</span><span>; </span><span>flush</span>(); <span>//</span><span>强制刷新程序缓存到浏览器缓存</span> <span>sleep</span>(1); <span>//</span><span>休眠1秒钟,http连接未断开,每隔1秒输出$i</span> }
-------------------------------------------------- -------------------------------------------------- --------
Mainly include:
① Universal caching technology ② Page caching ③ Time-triggered cache ④ Content-triggered cache ⑤ Static cache (generate html files)
⑥ Memory cache ⑦ PHP buffer ⑧ MYSQL cache ⑨ Based on reverse proxy Web caching, DNS polling
But the commonly used ones are ①②④. Others are used when the website has a large amount of data and has many interactions.
is used to reduce the pressure on the server. Reference: blog.163.com/.. .44905/
This depends on your actual situation. There are file cache, database cache, and memcache cache. . . . .

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。

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。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

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。

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。

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。


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