PSR is a series of specifications about PHP development. There are several versions. I learned it superficially, but I still hope to check the specifications from time to time. In order to facilitate memory and follow, I picked out the necessary keywords and made a Simply necessary normative records. (Just a brick mover...) PSR-0(deprecated) PSR-1 Basic Code Specification PSR-2 Code Style Specification PSR-2 Supplementary Documentation PSR-3 log interface specification PSR-4 automatically loaded PSR-5 and PSR-6 voting has not passed yet must PSR-1 Basic Code Specificationphp code file must start with PHP code files must be encoded in UTF-8 without BOM; Namespaces and classes must comply with PSR’s autoloading specification: one of PSR-0 or PSR-4; The naming of classes must follow the StudlyCaps camel case naming convention starting with an uppercase letter; All letters of constants in the class must be capitalized, and words are separated by underscores; Method names must comply with camelCase-style camelCase naming convention starting with lowercase. PHP code must use long tag or = ?> short output tag; other custom tags must not be used. Namespace and class naming must comply with PSR-0. Code for PHP 5.3 and later versions must use formal namespaces. Each class is an independent file, and the namespace has at least one level: the top-level organization name (vendor name) PSR-2 coding style guideCode must follow the coding specifications in PSR-1. Code must be indented using 4 spaces instead of the tab key. Note: The advantage of using spaces instead of tab keys for indentation is to avoid confusion when comparing code differences, patching, reviewing code, and comments. Also, use spaces for indentation to make alignment easier. A blank line must be inserted after each namespace declaration statement and use declaration block. The opening curly brace ({) of the class must be written on its own line after the function declaration, and the closing curly brace (}) must also be written on its own line after the function body. The opening curly brace ({) of the method must be written on its own line after the function declaration, and the closing curly brace (}) must also be written on its own line after the function body. The properties and methods of the class must add access modifiers (private, protected and public), abstract and final must be declared before the access modifier, and static must be declared after the access modifier. There must be a space after the keyword of the control structure, but it must not be when calling a method or function. The opening brace ({) of the control structure must be written on the same line as the declaration, and the closing brace (}) must be written on its own line after the body. There must be no spaces after the opening left bracket and before the closing right bracket of the control structure. All PHP files must use Unix LF (linefeed) as the line terminator. All PHP files must end with a blank line. Pure PHP code files must omit the final ?> closing tag. There must not be more than one statement per line. There must be no extra spaces after non-blank lines. All PHP keywords must be in lowercase. The constants true, false and null must also be all lowercase. PSR-3 log interface specification PSR-4 automatic loading specificationA complete class name must have the following structure:
When loading the corresponding file based on the complete class name
PHP code should only define declarations such as classes, functions, constants, etc., or other operations that will produce subordinate effects (such as generating file output and modifying .ini configuration files, etc.). You can only choose one of the two; The attribute naming of the class can follow the camel case starting with upper case ($StudlyCaps), the camel case starting with lower case ($camelCase), or the underline delimited format ($under_score). This specification does not make it mandatory, but no matter which naming is followed methods should be consistent within a certain range. PSR-2The number of characters per line should be softly kept within 80. In theory, it must not exceed 120, but there must be no hard limit. Blank lines make it easier to read code and help break up code into chunks. code example PSR-2
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Calculating the total number of elements in a PHP multidimensional array can be done using recursive or iterative methods. 1. The recursive method counts by traversing the array and recursively processing nested arrays. 2. The iterative method uses the stack to simulate recursion to avoid depth problems. 3. The array_walk_recursive function can also be implemented, but it requires manual counting.

In PHP, the characteristic of a do-while loop is to ensure that the loop body is executed at least once, and then decide whether to continue the loop based on the conditions. 1) It executes the loop body before conditional checking, suitable for scenarios where operations need to be performed at least once, such as user input verification and menu systems. 2) However, the syntax of the do-while loop can cause confusion among newbies and may add unnecessary performance overhead.

Efficient hashing strings in PHP can use the following methods: 1. Use the md5 function for fast hashing, but is not suitable for password storage. 2. Use the sha256 function to improve security. 3. Use the password_hash function to process passwords to provide the highest security and convenience.

Implementing an array sliding window in PHP can be done by functions slideWindow and slideWindowAverage. 1. Use the slideWindow function to split an array into a fixed-size subarray. 2. Use the slideWindowAverage function to calculate the average value in each window. 3. For real-time data streams, asynchronous processing and outlier detection can be used using ReactPHP.

The __clone method in PHP is used to perform custom operations when object cloning. When cloning an object using the clone keyword, if the object has a __clone method, the method will be automatically called, allowing customized processing during the cloning process, such as resetting the reference type attribute to ensure the independence of the cloned object.

In PHP, goto statements are used to unconditionally jump to specific tags in the program. 1) It can simplify the processing of complex nested loops or conditional statements, but 2) Using goto may make the code difficult to understand and maintain, and 3) It is recommended to give priority to the use of structured control statements. Overall, goto should be used with caution and best practices are followed to ensure the readability and maintainability of the code.

In PHP, data statistics can be achieved by using built-in functions, custom functions, and third-party libraries. 1) Use built-in functions such as array_sum() and count() to perform basic statistics. 2) Write custom functions to calculate complex statistics such as medians. 3) Use the PHP-ML library to perform advanced statistical analysis. Through these methods, data statistics can be performed efficiently.

Yes, anonymous functions in PHP refer to functions without names. They can be passed as parameters to other functions and as return values of functions, making the code more flexible and efficient. When using anonymous functions, you need to pay attention to scope and performance issues.


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