About PHP+xdebug analysis of code performance bottlenecks

Public members can be accessed at will; 2. Private members can only be accessed within the class; 3. Protected members can be accessed in classes and subclasses; 4. Rational use can improve code security and maintainability.

Using MySQLi object-oriented method: establish a connection, preprocess UPDATE statements, bind parameters, execute and check the results, and finally close the resource. 2. Using MySQLi procedure method: connect to the database through functions, prepare statements, bind parameters, perform updates, and close the connection after processing errors. 3. Use PDO: Connect to the database through PDO, set exception mode, pre-process SQL, bind parameters, perform updates, use try-catch to handle exceptions, and finally release resources. Always use preprocessing statements to prevent SQL injection, verify user input, and close connections in time.

cURLinPHPenablessendingHTTPrequests,fetchingAPIdata,anduploadingfiles.Initializewithcurl_init(),setoptionslikeCURLOPT_URLandCURLOPT_RETURNTRANSFER,useCURLOPT_POSTforPOSTrequests,sendJSONwithproperheaders,handleerrorsviacurl_errno()andHTTPcodeswithcur

ToreadaCSVfileinPHP,usefopen()toopenthefile,fgetcsv()inalooptoreadeachrowasanarray,andfclose()tocloseit;handleheaderswithaseparatefgetcsv()callandspecifydelimitersasneeded,ensuringproperfilepathsandUTF-8encodingforspecialcharacters.

AJAXwithPHPenablesdynamicwebappsbysendingasynchronousrequestswithoutpagereloads.1.CreateHTMLwithJavaScriptusingfetch()tosenddata.2.BuildaPHPscripttoprocessPOSTdataandreturnresponses.3.UseJSONforcomplexdatahandling.4.Alwayssanitizeinputsanddebugviabro

Chrome bookmark editing is simple and practical. Users can enter the bookmark manager through the shortcut keys Ctrl Shift O (Windows) or Cmd Shift O (Mac), or enter through the browser menu; 1. When editing a single bookmark, right-click to select "Edit", modify the title or URL and click "Finish" to save; 2. When organizing bookmarks in batches, you can hold Ctrl (or Cmd) to multiple-choice bookmarks in the bookmark manager, right-click to select "Move to" or "Copy to" the target folder; 3. When exporting and importing bookmarks, click the "Solve" button to select "Export Bookmark" to save as HTML file, and then restore it through the "Import Bookmark" function if necessary.

isset()checksifavariableexistsandisnotnull,returningtrueevenforzero,false,oremptystringvalues;2.empty()checksifavariableisnull,false,0,"0","",orundefined,returningtrueforthese"falsy"values;3.isset()returnsfalsefornon-exi

Answer: Using the PHPMailer library to configure the SMTP server can enable sending mails through SMTP in PHP applications. PHPMailer needs to be installed, set up SMTP host, port, encryption method and authentication credentials of Gmail, write code to set sender, recipient, topic and content, enable 2FA and use application password to ensure that the server allows SMTP connection, and finally call the send method to send email.