Introduction
When a PHP script has output, the output control function can use these to control the output. This is useful in a number of different situations, especially for sending http headers to the browser after the script has started outputting data. The output control function does not affect the file header information sent by header() or setcookie(), only the data between functions like echo and PHP code blocks.
Note:
Due to defects in earlier versions, when upgrading from PHP4.1.x (4.2.x, 4.3.x), you must ensure that implicit_flush in php.ini is OFF, otherwise any use of ob_start() The output will be hidden in the output.
Basic usage
<?php ob_start(); echo "Hello\n"; setcookie("cookiename", "cookiedata"); ob_end_flush(); ?>
In the above example, the output of the echo function will be saved in the output buffer until ob_end_flush() is called. At the same time, the call to setcookie() also successfully stores a cookie without causing an error. (Under normal circumstances, after the data is sent to the browser, the http header information can no longer be sent.)
Output control function
flush — Flush the output buffer
ob_clean — Clear (erase) the output buffer
ob_end_clean — Clear (erase) the buffer and close the output buffer
ob_end_flush — Flush (send out) the contents of the output buffer and close the buffer
ob_flush — Flush (send) the contents of the output buffer
ob_get_clean — Get the current The contents of the buffer and delete the current output buffer.
ob_get_contents — Returns the contents of the output buffer
ob_get_flush — Flushes (sends out) the buffer contents, returns the content as a string, and closes the output buffer.
ob_get_length — Returns the length of the output buffer content
ob_get_level — Returns the nesting level of the output buffer mechanism
ob_get_status — Gets the status of all output buffers
ob_gzhandler — Used in ob_start to compress the output buffer Content callback function.
ob_implicit_flush — Turn on/off absolute flushing
ob_list_handlers — List all output handlers in use.
ob_start — Turn on the output control buffer
output_add_rewrite_var — Add URL rewriter values
output_reset_rewrite_vars — Reset URL rewriter values

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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