Things to note when using empty() function in php_PHP Tutorial
When you use empty() to judge the number 0, empty() will also return true. That is to say, if your variable may have the number 0, it will be better to use isset() to judge! !
On the surface, it is easy to misunderstand that the empty() function is a function that determines whether a string is empty. In fact, it is not, and I suffered a lot because of it.
The empty() function is used to test whether the variable has been configured. If the variable already exists, is a non-empty string, or is non-zero, a false value is returned; otherwise, a true value is returned. Therefore, when the value of the string is 0, true is also returned, which is to execute the statement inside empty. This is the trap.
The code is as follows
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$a=array("1"=>"ddf"); To determine whether a string is empty, you can determine it like this: if ($value=="") ...
* Format: bool empty (mixed var) * If the variable does not exist, return TRUE * If the variable exists and its value is "", 0, "0", NULL,, FALSE, array(), var $var; and an object without any attributes, then TURE
* Version: PHP 3, PHP 4, PHP 5 On the surface, it is easy to misunderstand that the empty() function is a function that determines whether a string is empty. In fact, it is not, and I suffered a lot because of it. The empty() function is used to test whether the variable has been configured. If the variable already exists, is a non-empty string, or is non-zero, a false value is returned; otherwise, a true value is returned. Therefore, when the value of the string is 0, true is also returned, which is to execute the statement inside empty. This is the trap. For example: Assume $value = 0; then empty($value)=false. I advise everyone to be careful about using the empty() function. To determine whether a string is empty, you can determine it like this: if ($value=="") ... Format: bool empty (mixed var) Function: Check whether a variable is empty Return value: If the variable does not exist, return TRUE If If the variable exists and its value is "", 0, "0", NULL,, FALSE, array(), var $var; and an object without any attributes, TRUE is returned. If the variable exists and its value is not "", 0, "0", NULL, FALSE, array(), var $var; and objects without any attributes, return FALSE Version: PHP 3, PHP 4, PHP 5 When you use empty to check the result returned by a function, an error will be reported: Fatal error: Can't use function return value in write contextFor example:
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echo empty(strlen('be-evil.org'));
Go to the PHP manual and see the following text where the empty function is described:
Note: empty() only checks variables as anything else will result in a parse error. In other words, the following will not work: empty(trim($name)).
empty() only tests variables, testing anything that is not a variable will result in a parsing error!
Therefore, we cannot use empty to directly detect the value returned by the function. The solution to the above example is as follows:
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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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