while
(PHP 4, PHP 5)
while loop is the simplest loop type in PHP. It behaves the same as while in C language. The basic format of the while statement is:
while (expr) statement
The meaning of the while statement is very simple. It tells PHP to repeatedly execute the nested loop statement as long as the value of the while expression is TRUE. The value of the expression is checked each time the loop starts, so even if the value changes during the loop statement, execution of the statement will not stop until the end of the loop. Sometimes if the value of the while expression is FALSE at the beginning, the loop statement will not be executed even once.
Like if statements, you can use curly braces to enclose a group of statements in a while loop, or use alternative syntax:
while (expr): statement ... endwhile;
The following two examples are exactly the same, both display the numbers 1 to 10:
<?php /* example 1 */ $i = 1; while ($i <= 10) { echo $i++; /* the printed value would be $i before the increment (post-increment) */ } /* example 2 */ $i = 1; while ($i <= 10): print $i; $i++; endwhile; ?>
do -while
(PHP 4, PHP 5)
do-while loop is very similar to while loop, except that the value of the expression is checked at the end of each loop instead of at the beginning. The main difference from a normal while loop is that the do-while loop statement is guaranteed to be executed once (the truth value of the expression is checked after each loop), but in a normal while loop this is not necessarily the case (the truth value of the expression Checked at the beginning of the loop, if it is FALSE at the beginning, the entire loop terminates immediately).
do-while loops have only one syntax:
<?php $i = 0; do { echo $i; } while ($i > 0); ?>
The above loop will run exactly once, because after the first loop, when the truth value of the expression is checked, its value is FALSE ($i is not greater than 0 ) causing the loop to terminate.
Experienced C language users may be familiar with a different do-while loop usage, which is to put the statement in do-while(0) and use the break statement inside the loop to end the execution loop. The following code snippet demonstrates this method:
<?php do { if ($i < 5) { echo "i is not big enough"; break; } $i *= $factor; if ($i < $minimum_limit) { break; } echo "i is ok"; /* process i */ } while(0); ?>
Don’t worry if you don’t understand it right away. You can still write powerful code without using this "feature". Since PHP 5.3.0, you can also use goto to break out of loops.

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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