Some information, such as information that often remains unchanged but can still change, is placed in the cache to speed up the display. This is very valuable. The so-called cache is generally understood to be some shared information stored on the server. information. It lives and dies with the server. When we save the cache, we can specify the time of the next update. For example, if we want to update every 5 minutes, we can record the time of the last update and compare it with the current time. If it is greater than 5 minutes, Read the database and update it, otherwise read the cached data directly. Of course, the cache needs to be activated by the client user and only needs to be activated once.
ob_start() function
ob_start() function: Open the output buffer.
Function format void ob_start(void)
Note: When the buffer is activated, all non-file header information from the PHP program will not be sent, but will be saved in the internal buffer. In order to output the contents of the buffer, you can use ob_end_flush() or flush() to output the contents of the buffer.
flush() function
Function format: flush()
Note: This function is frequently used and is very efficient.
string ob_get_contents() function
ob_get_contents: Returns the contents of the internal buffer.
Function format: string ob_get_contents(void)
Description: This function will return the contents of the current buffer. If the output buffer is not activated, it will return FALSE.
ob_get_length() function
ob_get_length: Returns the length of the internal buffer.
Function format: int ob_get_length(void)
Description: This function will return the length in the current buffer; like ob_get_contents, if the output buffer is not activated, it will return FALSE.
ob_end_clean() function
ob_end_clean: Delete the contents of the internal buffer and close the internal buffer.
Function format: void ob_end_clean(void)
Description: This function will not output the contents of the internal buffer but delete it.
ob_end_flush() function
ob_end_flush: Send the contents of the internal buffer to the browser and close the output buffer
Function format: void ob_end_flush(void)
Description: This function sends the contents of the output buffer (if any).
ob_implicit_flush() function
Function format: void ob_implicit_flush ([int flag])
Note: The buffer is turned off by default. After turning on absolute output, each script output is sent directly to the browser, and there is no need to call flush().

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。

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。

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。

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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