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  • PHP header location whitespace before php tag
    PHP header location whitespace before php tag
    The reason and solution for jumping does not take effect or prompting "headersalreadysent" error: 1. The whitespace character at the beginning of the file causes the header to fail, check and delete
    PHP Tutorial . Backend Development 734 2025-07-11 00:31:11
  • PHP sprintf format examples
    PHP sprintf format examples
    The sprintf() function in PHP is used to format strings and return results. 1. Format numbers to be formatted as fixed decimal places, you can use %.2f, %.1f and other formats to automatically round; 2. Complement and width control can be implemented through d or M, indicating complementary or fill spaces respectively; 3. String truncation and splicing use %.10s or .10s to limit length and alignment; 4. When using multiple parameters in a mixed manner, %s, %d, and %f correspond to strings, integers, and floating-point numbers, respectively, and the order must be consistent. This function is very practical in generating logs, reports and other scenarios, making the code more neat and controllable.
    PHP Tutorial . Backend Development 832 2025-07-11 00:27:21
  • PHP session not working on mobile or in some browsers
    PHP session not working on mobile or in some browsers
    PHP session fails on mobile phones or some browsers, mainly due to cookie settings, session ID delivery or cross-domain issues. 1. The SessionID is not saved or passed correctly. If the third-party cookies are disabled, the user disables the cookies or misses the sid, make sure to call session_start() and check the cookie settings. 2. Mobile browser policies are strict. For example, iOSSafari blocks third-party cookies in iframes. Iframes should avoid nesting key processes and unifying domain names. 3. The Session file is not read and written correctly. If the permissions are insufficient or multiple servers are not synchronized, you need to check the log and debug output to confirm consistency. 4. HTTPS
    PHP Tutorial . Backend Development 872 2025-07-11 00:20:21
  • How to use prepared statements with mysqli
    How to use prepared statements with mysqli
    PreparedstatementsinMySQLipreventSQLinjectionandimproveefficiencybyseparatingSQLlogicfromdatainputs.Tousethemeffectively:1)connecttothedatabase,2)preparetheSQLstatementwithplaceholders,3)bindparameterscorrectlybytype(sforstring,iforinteger,etc.),4)ex
    PHP Tutorial . Backend Development 866 2025-07-11 00:17:50
  • How to debug a PHP function?
    How to debug a PHP function?
    The key to debugging PHP functions is to master practical methods and tools. 1. First check whether the input parameters are correct, use var_dump or print_r to print parameter values, and confirm whether the type, format and default values ??are reasonable; 2. Turn on error reports (error_reporting and display_errors), display all error messages, and help position variables undefined and keys, etc.; 3. Segmented testing logic, and determine whether the code execution process and intermediate results are in line with expectations through temporary output or logging; 4. Use debugging tools such as Xdebug to cooperate with IDE to achieve breakpoint debugging, single-step execution, etc. to improve efficiency; 5. Maintain good code specifications to reduce naming confusion or unclear function responsibilities
    PHP Tutorial . Backend Development 316 2025-07-10 13:58:01
  • Explain PHP Exception catching and creating custom exceptions.
    Explain PHP Exception catching and creating custom exceptions.
    In PHP development, catch exceptions and customize exception classes to improve code robustness. 1. Use try to wrap error codes, catch catch and handle exceptions, throw manually exceptions; 2. Custom exception classes inherit Exceptions, such as DatabaseException, PermissionException, and targeted processing; 3. Get detailed error information through getMessage(), getCode(), getFile() and other methods for debugging, but the production environment needs to turn off sensitive output.
    PHP Tutorial . Backend Development 798 2025-07-10 13:57:41
  • PHP preg_match_all to find all matches in a string
    PHP preg_match_all to find all matches in a string
    ToextractalloccurrencesofapatternfromastringinPHP,usethepreg_match_allfunction;itscansthestringwitharegularexpressionandreturnsallmatchesinanarray.1.Thesyntaxispreg_match_all($pattern,$subject,$matches,$flags,$offset),where$patternistheregexwrappedin
    PHP Tutorial . Backend Development 592 2025-07-10 13:51:31
  • What is a 'pure function' and how to write one in PHP?
    What is a 'pure function' and how to write one in PHP?
    Pure functions are concepts in functional programming. They can be implemented in PHP by following specific rules. The core features include: 1. No side effects, no modification of global variables, object states or performing I/O operations; 2. The same input always returns the same output, and does not rely on external data such as time and random numbers; 3. Keep simple and focused, only process inputs and return results, and do not use reference modifications or static variables to retain state. For example, sum(int$a,int$b):int is a typical pure function that only depends on parameters and has no external influence.
    PHP Tutorial . Backend Development 430 2025-07-10 13:51:10
  • How to handle unicode and UTF-8 strings in PHP
    How to handle unicode and UTF-8 strings in PHP
    The following points should be noted when dealing with Unicode and UTF-8 characters in PHP: 1. UTF-8 is used uniformly in all links, including HTML pages, PHP file saving formats and database connections; 2. Use mb_string extension to process multi-byte characters and replace native string functions; 3. Add the JSON_UNESCAPED_UNICODE parameter to maintain UTF-8 output when encoding; 4. Use utf8mb4 character sets in database settings. PHP does not distinguish encoding by default, which can easily lead to garbled code or emoji exceptions. Therefore, it is necessary to ensure UTF-8 consistency from the input to the output, and correctly use relevant extensions and parameters to deal with character encoding issues.
    PHP Tutorial . Backend Development 198 2025-07-10 13:49:10
  • How to build RESTful APIs using PHP frameworks?
    How to build RESTful APIs using PHP frameworks?
    Common PHP frameworks for building RESTful APIs include Laravel, Lumen, and Slim. 1. Select the framework according to the project size. For example, Laravel is suitable for medium and large projects, Lumen is a lightweight and high-performance framework, and Slim is more suitable for small projects. 2. Define a routing structure that conforms to resource semantics, such as GET/users obtains all users, and GET/users/1 obtains the specified user. 3. Use the controller to process logic to keep the code neat and define the route through Route::apiResource or manual registration. 4. Unifiedly return the JSON response format, including status code, message and data body, and improve interface consistency. 5. Add authentication such as JWT or L
    PHP Tutorial . Backend Development 256 2025-07-10 13:46:30
  • PHP header location ajax call not working
    PHP header location ajax call not working
    The reason why header('Location:...') in AJAX request is invalid is that the browser will not automatically perform page redirects. Because in the AJAX request, the 302 status code and Location header information returned by the server will be processed as response data, rather than triggering the jump behavior. Solutions are: 1. Return JSON data in PHP and include a jump URL; 2. Check the redirect field in the front-end AJAX callback and jump manually with window.location.href; 3. Ensure that the PHP output is only JSON to avoid parsing failure; 4. To deal with cross-domain problems, you need to set appropriate CORS headers; 5. To prevent cache interference, you can add a timestamp or set cache:f
    PHP Tutorial . Backend Development 589 2025-07-10 13:46:11
  • is a php array passed by value or by reference
    is a php array passed by value or by reference
    In PHP, arrays are passed by value by default, but the original array can be modified by reference pass. 1. By default, a copy is created when an array is passed as a parameter, and the modifications within the function will not affect the external array; 2. Use the & symbol to explicitly pass by reference, so that the modifications to the array in the function will be reflected to the outside; 3. Since PHP7, the copy-on-write mechanism is used to optimize performance, and the array is only actually copied when it is modified; 4. Return the array always returns a copy, even if the original array is passed in as a reference; 5. For large data sets that need to be frequently modified, it is recommended to use objects to replace the array to obtain behavior similar to reference passing.
    PHP Tutorial . Backend Development 981 2025-07-10 13:41:31
  • Discuss the benefits of using PDO over mysql_ functions (deprecated) for database interaction in php.
    Discuss the benefits of using PDO over mysql_ functions (deprecated) for database interaction in php.
    UsingPDOinsteadofmysqlfunctionsinPHPofferssignificantadvantagesincludingenhancedsecuritythroughpreparedstatements,databaseabstractionwithsupportformultipledatabases,improvederrorhandling,andanobject-orientedinterfacewithadvancedfeatures.1)PDO’sprepar
    PHP Tutorial . Backend Development 824 2025-07-10 13:41:10
  • PHP undefined index in foreach loop
    PHP undefined index in foreach loop
    The reason for the "undefinedindex" error in PHP's foreach loop is that the key that does not exist in the array is accessed. Common reasons include inconsistent array structure, unreliable data sources, and the use of uninitialized variables as arrays. To avoid error reports, 1. You can use isset() to check whether the key exists; 2. Use array_key_exists() to determine whether the key actually exists; 3. PHP7 can provide default values ??with empty merge operators. Situations that are easy to ignore include the risk of multiple key access in nested structures, and nested judgments should be made or a more concise ?? operator should be used. The key to solving this problem is to ensure that the array structure is correct and to perform existence verification before accessing the key.
    PHP Tutorial . Backend Development 540 2025-07-10 13:40:50

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