PHP implements open source Hadoop distributed storage and computing

There are three common methods for PHP comment code: 1. Use // or # to block one line of code, and it is recommended to use //; 2. Use /.../ to wrap code blocks with multiple lines, which cannot be nested but can be crossed; 3. Combination skills comments such as using /if(){}/ to control logic blocks, or to improve efficiency with editor shortcut keys, you should pay attention to closing symbols and avoid nesting when using them.

PHP comparison operators need to pay attention to type conversion issues. 1. Use == to compare values only, and type conversion will be performed, such as 1=="1" is true; 2. Use === to require the same value as the type, such as 1==="1" is false; 3. Size comparison can be used on values and strings, such as "apple"

There are two main ways to create arrays in PHP: use the array() function or [] abbreviation. The latter is recommended because it is concise and easy to read. When accessing array elements, you need to distinguish between index arrays and associative arrays, and be careful to avoid errors caused by access to undefined subscripts; operating arrays include adding, modifying, deleting and finding elements, adding available empty subscripts or specifying keys, modifying direct assignment, deleting use unset(), and determining whether the key or value exists using isset() and in_array() respectively.

Defining constants in PHP, const is more suitable for constant definitions inside classes, and define() is more flexible and suitable for global or dynamic definitions. 1.const is a language structure, and must be a compile-time constant expression when defined, which is suitable for class or global namespaces; define() is a function, and the value can be the result of runtime calculation. 2.const is affected by the namespace, and the constants defined by define() are visible globally by default. 3. The const structure is clear and the IDE is good, which is suitable for object-oriented design; define() has high flexibility but may have higher maintenance costs. 4. define() supports runtime condition judgment and dynamic definition, but const does not support it. Therefore, class-related constants preferentially use co

There are three common ways to use PHP comments: single-line comments are suitable for briefly explaining code logic, such as // or # for the explanation of the current line; multi-line comments /*...*/ are suitable for detailed description of the functions or classes; document comments DocBlock start with /** to provide prompt information for the IDE. When using it, you should avoid nonsense, keep updating synchronously, and do not use comments to block codes for a long time.

Comments are crucial in code because they improve the readability and maintenance of the code, especially in projects like PHP that are multi-collaborative and long-term maintenance. Reasons for writing comments include explaining “why do this” to save debugging time and be friendly to newbies and reduce communication costs. The representation of good comments includes explaining the role of functions or classes to explain complex logic intent marking to-dos or potential problems, and writing API interface documentation annotations. Typical manifestations of bad comments include repeated code content comments that are inconsistent with code and using comments to cover up bad code and retaining old information. Suggestions for writing comments include prioritizing comments "why" keeping comments synced with code Use a unified format to avoid emotional statements and consider optimizing code rather than relying on comments when the code is difficult to understand.

The first step is to select the integrated environment package XAMPP or MAMP to build a local server; the second step is to select the appropriate PHP version according to the project needs and configure multiple version switching; the third step is to select VSCode or PhpStorm as the editor and debug with Xdebug; in addition, you need to install Composer, PHP_CodeSniffer, PHPUnit and other tools to assist in development.

Writing good code and annotations can improve project maintainability and professionalism. 1.CleanCode emphasizes clear naming, single responsibilities and structures, so that it is easy for others to understand; 2. Comments should explain "why" rather than duplicate code functions; 3. PHP comments should cover class descriptions, method parameters, and key logical backgrounds; 4. Practical suggestions include using meaningful variable names, unified annotation style, and using tool specifications.