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 Escape Characters
Mastering String Literals: The Nuances of PHP Escape Sequences
Doublequotesinterpretescapesandvariables,singlequoteskeepthingsliteral;usedouble-quotedstringsfordynamiccontentwithvariablesandescapesequenceslike\nor$,usesingle-quotedforrawtexttoavoidunintendedparsing,applyheredocformulti-lineinterpolate
Aug 01, 2025 am 07:38 AM
Context is King: Tailoring Escape Strategies for HTML, JSON, and SQL Output
ForHTMLoutput,applycontext-awareescaping:useHTMLentityencodingfortextandattributes,andcombinewithJavaScriptescapinginscripts;2.ForJSON,alwaysusebuilt-inserializersandescapespecialcharacterslike
Jul 28, 2025 am 04:43 AM
Beyond `addslashes()`: Contextual Escaping for Robust SQL Injection Defense
SQL injection protection cannot rely on addslashes() because it does not process multi-byte encoding and only escapes finite characters, which is easily bypassed; preprocessing statements (such as parameterized queries for PDO or MySQLi) should be used to separate the data from SQL logic to ensure that the input is not parsed into code; if preprocessing cannot be used, database-specific escape functions (such as real_escape_string and setting the correct character set), identifier whitelist or quotation mark wrapping, integer input casting and other methods should be used according to the context to achieve hierarchical defense.
Jul 26, 2025 am 02:55 AM
A Comparative Analysis: `addslashes()` vs. `htmlspecialchars()` vs. `mysqli_real_escape_string()`
addslashes() should be avoided for SQL escapes because it is not safe and not protected from SQL injection; htmlspecialchars() is used for HTML output to prevent XSS attacks; mysqli_real_escape_string() can be used for string escapes in MySQL queries, but is only a suboptimal option when preprocessing statements cannot be used. 1. addslashes() is outdated and unsafe and should not be used for SQL escape in modern applications; 2. htmlspecialchars() should be used when outputting user input and outputting to HTML to prevent XSS; 3. mysqli_real_escape_string(
Jul 27, 2025 am 04:27 AM
Decoding the Escape: Handling Slashes and Special Characters in JSON with PHP
Correctly dealing with JSON slashes and special characters in PHP requires understanding the escape mechanism and using appropriate options. 1.json_encode() will automatically escape double quotes and backslashes. The additional backslashes displayed in the output are required for legal JSON format and will return to normal after parsing; 2. Use JSON_UNESCAPED_SLASHES to avoid slashes being escaped, making the URL clearer; 3. Use JSON_UNESCAPED_UNICODE to retain Unicode characters such as Chinese and emoji instead of converting them to \uXXXX sequences; 4. Ensure that the input is UTF-8 encoding and set header('Content-Type:application/jso
Jul 28, 2025 am 04:41 AM
The Art of the Backslash: Demystifying Escape Characters in PHP Regular Expressions
TomasterbackslashesinPHPregex,understandthattwolayersofparsingoccur:PHPprocessesescapesequencesfirst,thentheregexenginedoes;2.UsesinglequotesforregexpatternstoavoidPHPinterpretingescapeslike\basbackspace;3.Indoublequotes,doublethebackslashes(e.g.,&qu
Jul 27, 2025 am 03:18 AMPHP Numbers
Escape Character Behavior in PHP's Heredoc and Nowdoc Syntaxes
Heredoc handles variable interpolation and basic escape sequences such as \n, \t, \\, \$, but does not process \" or \', while Nowdoc does not perform variable interpolation and any escape processing. All contents, including \n and variables are output literally; 1. Variables such as $name will be replaced, \\n will be parsed as newlines; 2. $name and \n are kept as is true in Nowdoc; 3. No escape quotes are required for both; 4. The end identifier must occupy one line and no leading spaces. PHP7.3 allows the use of spaces to indent the end identifier. Therefore, Heredoc is suitable for multi-line strings that need to be formatted, and Nowdoc is suitable for outputting original content such as SQL or JavaScript.
Jul 26, 2025 am 09:45 AM
Demystifying Floating-Point Inaccuracies in PHP Applications
The problem of inaccurate floating point numbers is common in PHP, especially in financial calculations or precise comparisons. The root cause is that decimal decimals cannot be stored accurately in binary floating point representation (IEEE754 standard), resulting in results such as 0.1 0.2≠0.3; 1. When comparing floating point numbers equality, you should use tolerance values (epsilon) instead of directly using ==; 2. Financial calculations should avoid using floating point numbers, and instead use integers (such as in units of division) or BCMath extension; 3. BCMath performs arbitrary precision calculations through strings, which are suitable for high-precision scenarios, but have low performance; 4. It should be noted that PHP type conversion may implicitly convert strings or integers to floating point numbers to introduce errors; in short, inaccurate floating point numbers is a general calculation problem, but in
Jul 26, 2025 am 09:41 AM
Performance Profiling: The Cost of Integer, Float, and Arbitrary Precision Operations
IntegeroperationsarefastestduetonativeCPUsupport,makingthemidealforcounters,indexing,andbitoperations;1.useintegerswhenrangepermitsforoptimalspeedandmemory;floating-pointoperations(float32/float64)areslightlyslowerbutstillefficientviaFPU/SIMD,thoughs
Jul 29, 2025 am 04:30 AM
Exploring the Native BigInt Support in Modern PHP
PHPdoesnothaveanativebigintscalartype,butstartingwithPHP8.1,theexperimental\Number\BigIntclassprovidesarbitrary-precisionintegersupportwhenthebcmathextensionisenabled;1)itoffersmethodslikeadd(),sub(),andmul()forarithmetic,2)avoidsprecisionlossfromint
Jul 28, 2025 am 04:37 AM
The Perils and Power of PHP's Numeric Type Juggling and Coercion
PHP's loose type system is both powerful and dangerous in numeric type conversion. 1. When using loose comparison (==), PHP will convert non-numeric strings to 0, resulting in 'hello'==0 to true, which may cause security vulnerabilities. Strict comparisons (===) should always be used when needed. 2. In arithmetic operation, PHP will silently convert the string, such as '10apples' becomes 10, and 'apples10' becomes 0, which may cause calculation errors. The input should be verified using is_numeric() or filter_var(). 3. In the array key, a numeric string such as '123' will be converted into an integer, causing '007' to become 7, and the format is lost, which can be avoided by adding a prefix. 4. Function parameters
Jul 26, 2025 am 09:38 AM
Advanced Number Formatting for Internationalization and Readability
UseIntl.NumberFormatwithuser-specificlocalesforcorrectdigitgroupinganddecimalseparators.2.Formatcurrencyusingstyle:'currency'withISO4217codesandlocale-specificsymbolplacement.3.ApplycompactnotationforlargenumberstoenhancereadabilitywithunitslikeMor??
Jul 27, 2025 am 04:32 AM
From `mt_rand` to `random_int`: Generating Cryptographically Secure Numbers
mt_rand()isnotsecureforcryptographicpurposesbecauseitusestheMersenneTwisteralgorithm,whichproducespredictableoutput,maybepoorlyseeded,andisnotdesignedforsecurity.2.Forsecurerandomnumbergeneration,userandom_int()instead,asitdrawsfromtheoperatingsystem
Jul 28, 2025 am 04:42 AM
Working with Binary, Octal, and Hexadecimal Number Systems in PHP
PHPsupportsbinary,octal,andhexadecimalnumbersystemsusingspecificprefixesandconversionfunctions.1.Binarynumbersareprefixedwith0b(e.g.,0b1010=10indecimal).2.Octalnumbersuse0or0o(e.g.,012or0o12=10indecimal).3.Hexadecimalnumbersuse0x(e.g.,0xA=10indecimal
Aug 01, 2025 am 07:38 AM
PHP Integer Overflow: A Silent Threat on 32-bit vs. 64-bit Systems
IntegeroverflowinPHPoccurswhenanintegerexceedstheplatform'smaximumvalue,causingittobecasttoafloat,whichcanleadtoprecisionlossandunexpectedbehavior.On32-bitsystems,themaximumintegeris2,147,483,647,whileon64-bitsystems,itis9,223,372,036,854,775,807.Whe
Jul 26, 2025 am 09:39 AM
Unlocking Performance with Bitwise Operations on PHP Integers
BitwiseoperationsinPHParefast,CPU-leveloperationsthatoptimizeperformancewhenhandlingintegers,especiallyforflags,permissions,andcompactdatastorage.2.Usebitwiseoperatorslike&,|,^,~,tomanipulateindividualbits,enablingefficientbooleanflagmanagementwi
Jul 29, 2025 am 02:44 AM
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