


Methods and precautions for implementing long connections based on PHP_PHP Tutorial
PHP can cancel the PHP script timeout limit through set_time_limit(0); to achieve the effect of long connection.
The example code is as follows:
echo "Output every 3 seconds
";
set_time_limit(0); //Ensure that the php program does not timeout and exit
while(1) {
echo date("H:i:s")."
";
ob_flush();
flush(); //Refresh and output PHP buffer data
sleep(3); //Delay 3 seconds
}
?>
Sample code 2:
set_time_limit(0);
header("Connection:Keep-Alive");
header("Proxy-Connection:Keep-Alive");
for($i=0;$i
print 'text'.$i.'
';
ob_flush();
flush();
sleep(1);
clearstatcache();
}
Ob_flush(); flush(); is called here to force the output data to the buffer, so that the data can be returned to the browser in time before the step returns. In addition, there are some particularly easy mistakes in the use of flush and ob_flush, resulting in the inability to refresh the output buffer.
1. The correct order of flush and ob_flush, the correct order is, ob_flush first and then flush, as follows:
ob_flush();
flush();
If the operating system of the web server is a windows system, there will be no problem if the order is reversed or ob_flush() is not used. But on Linux systems, the output buffer cannot be flushed.
2. Before using ob_flush(), make sure the previous content size is enough to 4069 characters.
The output_buffering of some web servers defaults to 4069 characters or larger, that is, the output content must reach 4069 characters before the server flushes the output buffer. In order to ensure that the flush is effective, it is best to have the following statement before the ob_flush() function:
print str_repeat(" ", 4096);
to ensure the output_buffering value is reached.
for ($i=10; $i>0; $i--)
{
echo $i.'
';
ob_flush();
flush();
sleep(1);
}
ob_end_flush();

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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