PHP Tutorial
In this tutorial, you will be introduced to PHP from scratch, master the necessary skills for web development, and build your own dynamic website.
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PHP Data Types
The Perils of Precision: Handling Floating-Point Numbers in PHP
0.1 0.2!==0.3inPHPduetobinaryfloating-pointprecisionlimitations,sodevelopersmustavoiddirectcomparisonsanduseepsilon-basedchecks,employBCMathorGMPforexactarithmetic,storecurrencyinintegerswhenpossible,formatoutputcarefully,andneverrelyonfloatprecision
Jul 26, 2025 am 09:41 AM
PHP 8.1 Enums: A New Paradigm for Type-Safe Constants
Enums introduced in PHP8.1 provides a type-safe constant collection, solving the magic value problem; 1. Use enum to define fixed constants, such as Status::Draft, to ensure that only predefined values are available; 2. Bind enums to strings or integers through BackedEnums, and support conversion from() and tryFrom() between scalars and enums; 3. Enums can define methods and behaviors, such as color() and isEditable(), to enhance business logic encapsulation; 4. Applicable to static scenarios such as state and configuration, not for dynamic data; 5. It can implement the UnitEnum or BackedEnum interface for type constraints, improve code robustness and IDE support, and is
Jul 28, 2025 am 04:43 AM
Memory Management and PHP Data Types: A Performance Perspective
PHP's memory management is based on reference counting and cycle recycling. Different data types have a significant impact on performance and memory consumption: 1. Integers and floating-point numbers have small memory usage and the fastest operation, and should be used for numerical operations first; 2. Strings adopt a write-on-write copy mechanism, but large strings or frequent splicing will cause performance problems, so it is advisable to use implode optimization; 3. Array memory overhead is large, especially large or nested arrays. Generators should be used to process large data sets and release variables in a timely manner; 4. Objects are passed in reference mode, and instantiation and attribute access are slow, which is suitable for scenarios where behavioral encapsulation is required; 5. Resource types need to be manually released, otherwise it may lead to system-level leakage. In order to improve performance, data types should be selected reasonably, memory should be released in time, and large data should be avoided by global variables.
Jul 28, 2025 am 04:42 AM
Unraveling PHP's Type Juggling: A Guide to `==` vs. `===`
==performsloosecomparisonwithtypejuggling,===checksbothvalueandtypestrictly;1."php"==0istruebecausenon-numericstringsconvertto0,2.emptystrings,null,false,and0arelooselyequal,3.scientificnotationlike"0e123"=="0e456"cancau
Jul 28, 2025 am 04:40 AM
Understanding the `callable` Pseudo-Type and Its Implementation
AcallableinPHPisapseudo-typerepresentinganyvaluethatcanbeinvokedusingthe()operator,usedprimarilyforflexiblecodeincallbacksandhigher-orderfunctions;themainformsofcallablesare:1)namedfunctionslike'strlen',2)anonymousfunctions(closures),3)objectmethodsv
Jul 27, 2025 am 04:29 AMPHP Strings
The Life of a Variable: PHP's Internal `zval` Structure Explained
PHP uses zval structure to manage variables. The answer is: 1. zval contains values, types and metadata, with a size of 16 bytes; 2. When the type changes, only the union and type information need to be updated; 3. Complex types refer to structures with reference counts through pointers; 4. When assigning values, copy is used to optimize memory; 5. References make variables share the same zval; 6. Recycling references are processed by a special garbage collector. This explains the underlying mechanism of PHP variable behavior.
Jul 27, 2025 am 03:47 AM
The Nuances of String Comparison in PHP: `==` vs. `strcmp()` vs. `strnatcmp()`
Avoid==forstringcomparisonduetotypejuggling,whichcancauseunexpectedresultslike"0e12345"=="0e67890"beingtrue;2.Usestrcmp()forreliable,case-sensitive,lexicographicalcomparisonthatreturns0forequalstrings,negativeifthefirstisless,andp
Jul 27, 2025 am 04:01 AM
Character-Level String Manipulation and its Performance Implications
Character-levelstringmanipulationcanseverelyimpactperformanceinimmutable-stringlanguagesduetorepeatedallocationsandcopying;1)avoidrepeatedconcatenationusing =inloops,insteadusemutablebufferslikelist ''.join()inPythonorStringBuilderinJava;2)minimizein
Jul 26, 2025 am 09:40 AM
Beyond JSON: Understanding PHP's Native String Serialization
PHP's native serialization is more suitable for PHP's internal data storage and transmission than JSON, 1. Because it can retain complete data types (such as int, float, bool, etc.); 2. Support private and protected object properties; 3. Can handle recursive references safely; 4. There is no need for manual type conversion during deserialization; 5. It is usually better than JSON in performance; but it should not be used in cross-language scenarios, and unserialize() should never be called for untrusted inputs to avoid triggering remote code execution attacks. It is recommended to use it when it is limited to PHP environment and requires high-fidelity data.
Jul 25, 2025 pm 05:58 PM
Unpacking Binary Data: A Practical Guide to PHP's `pack()` and `unpack()`
PHP's pack() and unpack() functions are used to convert between PHP variables and binary data. 1.pack() packages variables such as integers and strings into binary data, and unpack() unpacks the binary data into PHP variables. Both rely on format strings to specify conversion rules. 2. Common format codes include C/c (8-bit with/unsigned characters), S/s (16-bit short integer), L/l/V/N (32-bit long integer, corresponding to different endianness), f/d (floating point/double precision), a/A (fill string), x (null byte), etc. 3. Endite order is crucial: V represents small-endian (Intel), N represents large-endian (network standard). V should be used first when communicating across platforms.
Jul 25, 2025 pm 05:59 PM
Navigating the Labyrinth of PHP String Encoding: UTF-8 and Beyond
UTF-8 processing needs to be managed manually in PHP, because PHP does not support Unicode by default; 1. Use the mbstring extension to provide multi-byte security functions such as mb_strlen, mb_substr and explicitly specify UTF-8 encoding; 2. Ensure that database connection uses utf8mb4 character set; 3. Declare UTF-8 through HTTP headers and HTML meta tags; 4. Verify and convert encoding during file reading and writing; 5. Ensure that the data is UTF-8 before JSON processing; 6. Use mb_detect_encoding and iconv for encoding detection and conversion; 7. Preventing data corruption is better than post-repair, and UTF-8 must be used at all levels to avoid garbled code problems.
Jul 26, 2025 am 09:44 AM
Defensive String Handling: Preventing XSS and Injection Attacks in PHP
TodefendagainstXSSandinjectioninPHP:1.Alwaysescapeoutputusinghtmlspecialchars()forHTML,json_encode()forJavaScript,andurlencode()forURLs,dependingoncontext.2.Validateandsanitizeinputearlyusingfilter_var()withappropriatefilters,applywhitelistvalidation
Jul 25, 2025 pm 06:03 PM
Advanced Pattern Matching with PHP's PCRE Functions
PHP's PCRE function supports advanced regular functions, 1. Use capture group() and non-capture group (?:) to separate matching content and improve performance; 2. Use positive/negative preemptive assertions (?=) and (?!)) and post-issue assertions (???)) and post-issue assertions (??
Jul 28, 2025 am 04:41 AM
Memory-Efficient String Processing for Large Datasets in PHP
Processlargefilesline-by-lineorinchunksusingfgets()orfread()insteadofloadingentirefilesintomemorywithfile()orfile_get_contents().2.Minimizeunnecessarystringcopiesbyavoidingchainedstringfunctions,breakingdownoperations,andusingunset()onlargestringswhe
Jul 26, 2025 am 09:42 AM
Harnessing the Power of Regular Expression Callbacks with `preg_replace_callback`
preg_replace_callback is a powerful tool in PHP for dynamic string replacement, which implements complex logic by calling custom functions for each regular match. 1. The function syntax is preg_replace_callback($pattern,$callback,$subject), where $callback can dynamically process the matching content; 2. It can be used for numerical transformation, such as replacing [10] with [20]; 3. Supporting multi-capture group operations, such as converting the YYYY-MM-DD format date to "May15,2024"; 4. Combining the use keyword can maintain the status, such as adding an incremental number to each word; 5. Applicable to
Jul 30, 2025 am 05:37 AM
Strings as Value Objects: A Modern Approach to Domain-Specific String Types
Rawstringsindomain-drivenapplicationsshouldbereplacedwithvalueobjectstopreventbugsandimprovetypesafety;1.Usingrawstringsleadstoprimitiveobsession,whereinterchangeablestringtypescancausesubtlebugslikeargumentswapping;2.ValueobjectssuchasEmailAddressen
Aug 01, 2025 am 07:48 AM
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