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  • php array remove duplicates from multidimensional array
    php array remove duplicates from multidimensional array
    When dealing with PHP multi-dimensional array deduplication, you cannot use array_unique directly, and other methods are required. 1. Use serialize and unserialize to combine array_map to serialize the sub-array into a string and then deduplicate it, and then restore it to an array, which is suitable for two-dimensional arrays; 2. Customize the comparison function arrayUnique, which manually compares each element through traversal, which is highly flexible but less efficient; 3. Pay attention to the fact that the key names and order will affect the uniqueness judgment, and it is recommended to unify the structure or compare according to specific fields; 4. If deduplicate it according to a certain field (such as id), you can use a temporary array to record the existing field values, and only the items that appear for the first time are retained. The selection method should be determined based on the data structure and performance requirements.
    PHP Tutorial . Backend Development 976 2025-07-09 00:28:11
  • How to check if a PHP session is active?
    How to check if a PHP session is active?
    TocheckifaPHPsessionisactive,usesession_status()whichreturnsPHP_SESSION_ACTIVEifasessionisrunning.1.Usesession_status()===PHP_SESSION_ACTIVEforreliabledetection.2.Avoidrelyingonisset($_SESSION)asitcanbemisleading.3.ForlegacyPHPversionsbefore5.4,usese
    PHP Tutorial . Backend Development 859 2025-07-09 00:26:31
  • How to escape a string for a database query in PHP
    How to escape a string for a database query in PHP
    The most direct and effective way to prevent SQL injection is to use parameterized queries. 1. Use PDO preprocessing statements to safely bind variables by naming placeholders and execute() methods; 2. Use mysqli's preprocessing function to bind parameters through the placeholders and bind_param() methods; 3. Manual escape strings are not recommended because there are security risks and are outdated; 4. Always verify and filter user input, combined with the built-in security mechanism of the framework to enhance security.
    PHP Tutorial . Backend Development 513 2025-07-09 00:22:21
  • PHP prepared statement for DELETE query
    PHP prepared statement for DELETE query
    Performing DELETE operations using PHP's preprocessing statements prevents SQL injection and ensures that deletion is safe and controllable. 1. Establish a reliable database connection. It is recommended to use MySQLi or PDO; 2. Use placeholders (?) to write DELETE preprocessing statements and bind parameters through bind_param to ensure type matching; 3. Call execute() to perform deletion operations; 4. Optionally check affected_rows to confirm whether the deletion takes effect; 5. Pay attention to calling execute() multiple times during batch deletion, and explicitly close the statement to standardize the operation process.
    PHP Tutorial . Backend Development 1018 2025-07-09 00:19:41
  • How to handle Date and Time operations in PHP?
    How to handle Date and Time operations in PHP?
    It is recommended to use the DateTime class for PHP processing date and time. 1. Use the DateTime class to replace old functions, with clear structure and support time zone settings; 2. Use DateTime to manage time and specify the target time zone before output; 3. Use DateInterval to calculate the time difference and obtain complete information such as year, month, and day; 4. Pay attention to avoid the influence of mixed use of date() functions, hard-coded time strings and daylight saving time.
    PHP Tutorial . Backend Development 295 2025-07-09 00:17:31
  • PHP header location with variables not working
    PHP header location with variables not working
    The main reasons for header jump failure include early output triggering, variable splicing errors and path configuration problems. 1. Output triggers in advance: Check whether there are echo/print/var_dump or file to introduce empty lines, and use ob_start() to buffer the output; 2. Variable splicing errors: Make sure that the variable has values ??and is formatted correctly, encode parameters with urlencode and print the verification URL; 3. Path or server problems: Confirm the path is correct and the domain name protocol matches, check the .htaccess/Nginx rewrite rules, manually test the URL access permissions and add exit termination script.
    PHP Tutorial . Backend Development 576 2025-07-09 00:14:00
  • How Do You Secure File Uploads in PHP?
    How Do You Secure File Uploads in PHP?
    TosecurelyhandlefileuploadsinPHP,youmusttreateveryfileasapotentialthreatandimplementmultipleprotectivemeasures.1.LimitfiletypesusingawhitelistandverifytheactualextensionafterrenaminginsteadofrelyingonMIMEtypes.2.Renamefileswithuniqueidentifierstoprev
    PHP Tutorial . Backend Development 436 2025-07-09 00:08:40
  • how to loop through php array
    how to loop through php array
    Common methods of traversing arrays by PHP include: 1. Use foreach to handle associative and indexed arrays, suitable for scenarios where indexes are not manually controlled; 2. Use for loops to traverse indexed arrays, suitable for situations where indexes need to be precisely controlled, but attention should be paid to avoid repeated calls to count() and non-continuous indexes; 3. While combined with each() for old versions of PHP traversal, but it has been deprecated in PHP8; 4.array_map is used to execute functions on each element and return a new array; 5.array_walk is used to directly modify the original array or execute side effects. Choosing the appropriate method according to the specific scenario can improve development efficiency and code readability.
    PHP Tutorial . Backend Development 945 2025-07-09 00:02:01
  • How Do You Pass Variables by Value vs. by Reference in PHP?
    How Do You Pass Variables by Value vs. by Reference in PHP?
    InPHP,variablesarepassedbyvaluebydefault,meaningfunctionsorassignmentsreceiveacopyofthedata,whilepassingbyreferenceallowsmodificationstoaffecttheoriginalvariable.1.Whenpassingbyvalue,changestothecopydonotimpacttheoriginal,asshownwhenassigning$b=$aorp
    PHP Tutorial . Backend Development 195 2025-07-08 02:42:41
  • What are some key features introduced in PHP 8 ?
    What are some key features introduced in PHP 8 ?
    PHP8 introduces a number of important new features, significantly improving performance, code readability and development experience. 1. JIT compilation improves execution speed, especially for CPU-intensive tasks, and is controlled through php.ini configuration; 2. Union types support more flexible type declarations, allowing direct definition of multiple parameter types; 3. Named parameters enhance the readability and security of function calls to avoid order errors; 4. Match expressions provide a more concise condition return method than switch, with strict comparison and non-penetration characteristics; 5. Constructor attribute improvement reduces boilerplate code, making class definition more concise; in addition, it also includes improvements such as throw expressions and attribute replacement annotations, making PHP8 more modern, powerful and easy to use overall. Although upgrades require investment,
    PHP Tutorial . Backend Development 451 2025-07-08 02:39:20
  • What are some key features introduced in PHP 7 ?
    What are some key features introduced in PHP 7 ?
    PHP7introducedmajorimprovementsincludingscalartypedeclarations,returntypedeclarations,thenullcoalescingoperator,spaceshipoperator,anonymousclasses,andperformanceenhancements.First,scalartypedeclarationsallowenforcingtypeslikeint,float,bool,andstringi
    PHP Tutorial . Backend Development 999 2025-07-08 02:37:20
  • How to handle File Uploads securely in PHP?
    How to handle File Uploads securely in PHP?
    To safely handle PHP file uploads, you need to verify the source and type, control the file name and path, set server restrictions, and process media files twice. 1. Verify the upload source to prevent CSRF through token and detect the real MIME type through finfo_file using whitelist control; 2. Rename the file to a random string and determine the extension to store it in a non-Web directory according to the detection type; 3. PHP configuration limits the upload size and temporary directory Nginx/Apache prohibits access to the upload directory; 4. The GD library resaves the pictures to clear potential malicious data.
    PHP Tutorial . Backend Development 750 2025-07-08 02:37:01
  • What are Interfaces and Abstract Classes in PHP?
    What are Interfaces and Abstract Classes in PHP?
    An interface is a contract that defines the methods that a class must implement. A class can implement multiple interfaces; an abstract class is a semi-finished class that cannot be instantiated and can contain abstract methods and concrete implementations. Subclasses can only inherit one abstract class. For example, the Logger interface specifies a log method, and FileLogger implements it; Animal abstract class has abstract method makeSound and concrete method sleep, and Dog inherits and implements makeSound. Use interfaces to define common behaviors, such as payment interfaces; use abstract classes to adapt to shared logic, such as public methods of animal systems. Other details: The interface method defaults to public; abstract classes can have constructors; PHP8 supports interface default methods.
    PHP Tutorial . Backend Development 647 2025-07-08 02:35:40
  • php get day of week
    php get day of week
    The method of getting the day of the week in PHP is as follows: 1. Use the date() function to match the 'w' or 'l' parameters to get the current week in the form of a number or English name respectively; 2. Convert it to Chinese week through a custom mapping array; 3. Use strtotime() to get the week of the specified date; 4. Pay attention to setting the time zone to ensure the accuracy of the results. For example, date('w') returns 0~6 to mean Sunday to Saturday, date('l') returns the complete English week name, and can output Chinese weekdays with a mapping array. When processing non-current dates, you need to use strtotime() to convert it to a timestamp and then pass it in date(). If the result is abnormal, check and set the correct time zone such as Asia/Shanghai.
    PHP Tutorial . Backend Development 701 2025-07-08 02:34:21

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