This article gives you a detailed analysis of the usage differences between php://output and php://stdout as well as sample code sharing. Friends in need can refer to it.
PHP includes a series of output streams starting with php://, such as php://stdin, php://stdout, etc. When I was looking at the code today, a question suddenly occurred to me: What is the difference between php://output and php://stdout?
Find the answer from PHP's official documentation. The explanations of the input streams php://stdin and php://input are as follows (the explanation of the output stream is too brief):
php://stdin
php://stdin, php://stdout and php://stderr allow direct access to the corresponding input or output stream of the PHP process. The stream references a duplicate file descriptor, so if you open php://stdin and later close it, you close only your copy of the descriptor-the actual stream referenced by STDIN is unaffected. Note that PHP exhibited buggy behavior in this regard until PHP 5.2.1. It is recommended that you simply use the constants STDIN, STDOUT and STDERR instead of manually opening streams using these wrappers.
php://stdin is read-only, whereas php://stdout and php://stderr are write-only.
php://input
php://input is a read-only stream that allows you to read raw data from the request body. In the case of POST requests, it is preferable to use php://input instead of $HTTP_RAW_POST_DATA as it does not depend on special php.ini directives. Moreover, for those cases where $HTTP_RAW_POST_DATA is not populated by default, it is a potentially less memory intensive alternative to activating always_populate_raw_post_data. php://input is not available with enctype=”multipart/form-data”.
The document does not directly explain the difference between the two. A careful comparison can yield the following information: 1. Both are read-only streams; 2. php://stdin is the standard input of the PHP process, and php://input is used to read the original data of the request body. With this information, how can we correctly understand the essential differences between the two?
Follow the input prompts of the php://stdin process, associate the execution process of the PHP process, and combine it with the differences in SAPI, you can get the main difference between the two: php://stdin is the input stream of the PHP process. Data may flow in during the execution life cycle (such as interactive input under CLI); php://input is the external input stream when PHP is executed. Generally, data can only be read once (see the implementation of SAPI for details). In the same way, we can get the difference between php://stdout and php://output: php://stdout is the standard output stream of the PHP process, and php://output is the returned result data stream.
The following code is used to verify the conclusion:
// file: test.php file_put_contents("php://output", "message sent by output" . PHP_EOL); file_put_contents("php://stdout", "message sent by stdout" . PHP_EOL); print("message sent by print" . PHP_EOL); echo "SAPI:" , PHP_SAPI , PHP_EOL;
The command line executes the file and the output is as follows:
message sent by output message sent by stdout message sent by print SAPI:cli
Browser side request, the output is as follows:
message sent by output message sent by print SAPI:fpm-fcgi
Under the command line, the standard output stream and result output stream of the PHP process are pointed to the terminal and all messages are printed. On the browser side, the output stream of the PHP process is ignored, and only the resulting data stream is sent to the web server. At the same time, the information of print and echo calls are sent to the result output stream as execution results, so they are displayed normally.
Finally, I would like to express my appreciation for the simplicity and practicality of PHP's built-in functions. One file_put_contents function can handle the stream writing operation. Changing to Java requires a lot of stream/writer code, and also saves the cumbersome C-style fopen/fwrite/fclose. .
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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。

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。


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