PHP's standard input and output

This article introduces the standard input and output of PHP, which has certain reference value. Now I share it with you. Friends in need can refer to it.

Brief introduction to the standard input and output of PHP

7 months ago ⋅ 956 ⋅ 11 ⋅ 0

##I want to use PHP in Sphere Online Judge today I came to challenge some questions online, which requires the use of standard input and output, but I am writing PHP recently and don’t want to use C to write. I usually submit forms when writing projects. I really haven’t considered this, so I took a look at the documentation.

The document is here: http://php.net/manual/zh/wrappers.php.php

1. PHP STDIN, Introduction to STDOUT and STDERR:

STDIN, STDOUT, STDERR command input and output streams are used to send messages to the console (linux shell terminal, windows cmd terminal) input and output content, they are open by default, you can directly read and write them, they can only be used in CLI (command-line interface, command line interface) mode, in Http mode, they are undefined.

And their open copies php://stdin, php://stdout, php://stderr cannot output the content to http browsing After testing, the content written to php://stderr will be entered into the error log of the default site, and the other two have no effect.

STDIN/STDOUT/STDERR Introduction:

Original stream	Stream open copy	Description
STDIN	php://stdin	Standard input (standard input), read-only, used to input content from the console;
STDOUT	php://stdout	Standard output (standard output), write-only, used to output to the consoleNormal Message;
STDERR	php://stderr	Error output (standard error), write-only, used to report to the console OutputError message；

It is officially recommended to use the constants STDIN, STDOUT and STDERR instead of their manually opened copy wrappers php://stdin, php://stdout and php: //stderr.

2. PHP STDIN usage:

"STDIN" in PHP language is used to read content from the console. When encountering this constant or opening it through the fopen() function php://stdinThe script will wait for the user to enter content until the user presses the Enter key to submit.

Write stdin.phpTest it:

<?php
echo "请输入内容:";
$jimmy = fgets(STDIN);
echo sprintf("输入的内容为: %s\n", $jimmy);
$demo = fopen(&#39;php://stdin&#39;, &#39;r&#39;);
echo "请输入: ";
$test = fread($demo, 12); //最多读取12个字符
echo sprintf("输入为: %s\n", $test);fclose($demo);

Run result:

请输入内容:sad
输入的内容为: sad

请输入: asdasdasdasdasdasd
输入为: asdasdasdasd（这里因为设置了最多读取12个字符，设置更多一些就可以完整显示）

3. PHP STDOUT usage:

PHP In the language, STDOUT is used to output standard information to the console; write to this constant or to php://stdout opened by the fopen() function. The content will be output directly to the standard output of the console; the content of the standard output can be redirected to the specified place using ">" or "1>" , such as files.

Similarly, let’s write a file to test it

<?php
fwrite(STDOUT, "通过STDOUT写入；\n");
$demo = fopen("php://stdout", "w");
fwrite($demo, "通过php://stdout写入；");
fclose($demo);

Run it:

☁  test  php demo.php > a.txt
☁  test  cat a.txt
通过STDOUT写入；
通过php://stdout写入；%                                                        ☁  test  php demo.php
通过STDOUT写入；
通过php://stdout写入；%                                                        ☁  test

4. PHP STDERR usage:

"STDERR" in PHP language Used to output error information to the console; content written to a constant or to "php://stderr" opened by the fopen() function will be directly output to the console's error output; The error output content can be redirected to a specified place, such as a file, using "2>"; the error output can also be directed to standard output using "2>&1" , merged with standard output.

Let’s test it

<?php
fwrite(STDERR, "STDERR写入的错误输出；\n");
fwrite(STDOUT, "STDOUT写入的正常输出；\n");
$stdout = fopen("php://stdout", "w");
fwrite($stdout, "php://stdout写入的正常输出；\n");
fclose($stdout);$stderr = fopen("php://stderr", "w");
fwrite($stderr, "php://stderr写入的错误输出；\n");
fclose($stderr);

Normal output and error output are directed to different files:

☁  test  php demo.php 1>demo.ok 2>demo.err
☁  test   cat demo.okSTDOUT写入的正常输出；
php://stdout写入的正常输出；☁  test   cat demo.errSTDERR写入的错误输出；
php://stderr写入的错误输出；

Normal output and error output are merged and directed to a unified file:

☁  test  php demo.php 1>AllInOne 2>&1☁  test  cat AllInOneSTDERR写入的错误输出；
STDOUT写入的正常输出；
php://stdout写入的正常输出；
php://stderr写入的错误输出；

Okay, now you can go to Sphere Online Judge to test the demo topic first

Write a code

<?php
    // your code here$x=0;while($x!=42){
   $x = fgets(STDIN);
   if($x!=42){
   echo sprintf("%d\n",$x);}}?>

Submit

Hahahaha, it’s totally ok. I no longer need to be limited to Java and C. I can challenge some questions with PHP. You can also try it

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