


Revealing the Detailed Analysis of PHP Image Upload Code_PHP Tutorial
When learning PHP, you may encounter the problem of uploading images in PHP. Here we will introduce the detailed PHP image upload code to solve this problem. I will share it with you here. The syntax of PHP is very simple. It is its simplicity that makes it the number one programming language on the Internet. You don't need to have a lot of knowledge to get started. For example, if you learn C language, you must have a good understanding of how each variable is defined, how pointers are operated, how memory is created and destroyed, etc.
The following is the complete PHP image upload code;
<ol class="dp-xml"> <li class="alt"><span><span class="tag"><span class="attribute">formenctype</span><span class="tag-name">formenctype</span><span>="multipart/form-data"</span><span class="attribute-value">action</span><span>=""</span><span class="attribute">method</span><span>=</span><span class="attribute-value">"post"</span><span class="tag">></span><span> </span></span><li class=""> <span></span><span class="tag"><span class="attribute">inputtype</span><span class="tag-name">inputtype</span><span>="hidden"</span><span class="attribute-value">name</span><span>="max_file_size"</span><span class="attribute">value</span><span>=</span><span class="attribute-value">"200000"</span><span class="tag">></span><span> </span></span> </li> <li class="alt"> <span></span><span class="tag"><span class="attribute">inputname</span><span class="tag-name">inputname</span><span>="userfile"</span><span class="attribute-value">type</span><span>="file"</span><span class="tag">></span><span> </span></span> </li> <li class=""> <span></span><span class="tag"><span class="attribute">inputtype</span><span class="tag-name">inputtype</span><span>="submit"</span><span class="attribute-value">name</span><span>="submit"</span><span class="attribute">value</span><span>=</span><span class="attribute-value">"上传文件"</span><span class="tag">></span><span> </span></span> </li> <li class="alt"> <span></span><span class="tag"></span><span class="tag-name">form</span><span class="tag">></span><span> </span> </li></span></li> <li class=""><span> </span></li> <li class="alt"> <span></span><span class="tag"></span><span class="tag-name">php</span><span> </span> </li> <li class=""> <span>$</span><span class="attribute">type</span><span>=</span><span class="attribute-value">array</span><span>("jpg","gif","bmp","jpeg","png"); </span> </li> <li class="alt"> <span>$</span><span class="attribute">uploaddir</span><span>=</span><span class="attribute-value">"./file/"</span><span>; </span> </li> <li class=""><span> </span></li> <li class="alt"><span>if(isset($_POST['submit'])) </span></li> <li class=""><span>{ </span></li> <li class="alt"><span>functiontexttype($name) </span></li> <li class=""><span>{ </span></li> <li class="alt"><span>returnsubstr(strrchr($name,'.'),1); </span></li> <li class=""><span>} </span></li> <li class="alt"><span>if(!in_array(strtolower(texttype($_FILES['userfile']['name'])),$type)) </span></li> <li class=""><span>{ </span></li> <li class="alt"> <span>$</span><span class="attribute">text</span><span>=</span><span class="attribute-value">implode</span><span>(",",$type); </span> </li> <li class=""> <span>echo"您只能上传以下类型文件:",$text,"</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span>"; </span></span> </li> <li class="alt"><span>} </span></li> <li class=""><span>else </span></li> <li class="alt"><span>{ </span></li> <li class=""> <span>if($_FILES['userfile']['size']</span><span class="tag"><span>="200000") </span></span> </li> <li class="alt"><span>{ </span></li> <li class=""> <span>$</span><span class="attribute">filename</span><span>=</span><span class="attribute-value">explode</span><span>(".",$_FILES['userfile']['name']); </span> </li> <li class="alt"> <span>$</span><span class="attribute">time</span><span>=</span><span class="attribute-value">date</span><span>("m-d-H-i-s"); </span> </li> <li class=""><span>$filename[0]=$time; </span></li> <li class="alt"> <span>$</span><span class="attribute">name</span><span>=</span><span class="attribute-value">implode</span><span>(".",$filename); </span> </li> <li class=""> <span>$</span><span class="attribute">uploadfile</span><span>=$uploaddir.$name; </span> </li> <li class="alt"><span>if(move_uploaded_file($_FILES['userfile']['tmp_name'],$uploadfile)) </span></li> <li class=""><span>{ </span></li> <li class="alt"> <span>echo"</span><span class="tag"><span class="tag-name">center</span><span class="tag">></span><span>您的文件已经上传完毕上传图片预览:</span><span class="tag"></span><span class="tag-name">center</span><span class="tag">></span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span class="tag"><span class="tag-name">center</span><span class="tag">></span><span class="tag"><span class="attribute">imgsrc</span><span class="tag-name">imgsrc</span><span>=</span><span class="attribute-value">'$uploadfile'</span><span class="tag">></span><span class="tag"></span><span class="tag-name">center</span><span class="tag">></span><span>"; </span></span><li class=""> <span>echo"</span><span class="tag"><span class="tag-name">br</span><span class="tag">></span><span class="tag"><span class="tag-name">center</span><span class="tag">></span><span class="tag"><span class="attribute">ahref</span><span class="tag-name">ahref</span><span>=</span><span class="attribute-value">'javascrīpt:history.go(-1)'</span><span class="tag">></span><span>继续上传</span><span class="tag"></span><span class="tag-name">a</span><span class="tag">></span><span class="tag"></span><span class="tag-name">center</span><span class="tag">></span><span>"; </span></span><li class="alt"><span>} </span></li> <li class=""><span>else </span></li> <li class="alt"><span>{ </span></li> <li class=""><span>echo"传输失败!"; </span></li> <li class="alt"><span>} </span></li> <li class=""><span>} </span></li> <li class="alt"><span>else </span></li> <li class=""><span>{ </span></li> <li class="alt"><span>echo"图片太大"; </span></li> <li class=""><span>} </span></li> <li class="alt"><span>} </span></li> <li class=""><span>} </span></li> <li class="alt"> <span></span><span class="tag">?></span><span> </span> </li></span></span> </li></span></span></span> </li> </ol>
The above is the detailed PHP image upload code, I hope it will be helpful to everyone.

PHPsessionscanstorestrings,numbers,arrays,andobjects.1.Strings:textdatalikeusernames.2.Numbers:integersorfloatsforcounters.3.Arrays:listslikeshoppingcarts.4.Objects:complexstructuresthatareserialized.

TostartaPHPsession,usesession_start()atthescript'sbeginning.1)Placeitbeforeanyoutputtosetthesessioncookie.2)Usesessionsforuserdatalikeloginstatusorshoppingcarts.3)RegeneratesessionIDstopreventfixationattacks.4)Considerusingadatabaseforsessionstoragei

Session regeneration refers to generating a new session ID and invalidating the old ID when the user performs sensitive operations in case of session fixed attacks. The implementation steps include: 1. Detect sensitive operations, 2. Generate new session ID, 3. Destroy old session ID, 4. Update user-side session information.

PHP sessions have a significant impact on application performance. Optimization methods include: 1. Use a database to store session data to improve response speed; 2. Reduce the use of session data and only store necessary information; 3. Use a non-blocking session processor to improve concurrency capabilities; 4. Adjust the session expiration time to balance user experience and server burden; 5. Use persistent sessions to reduce the number of data read and write times.

PHPsessionsareserver-side,whilecookiesareclient-side.1)Sessionsstoredataontheserver,aremoresecure,andhandlelargerdata.2)Cookiesstoredataontheclient,arelesssecure,andlimitedinsize.Usesessionsforsensitivedataandcookiesfornon-sensitive,client-sidedata.

PHPidentifiesauser'ssessionusingsessioncookiesandsessionIDs.1)Whensession_start()iscalled,PHPgeneratesauniquesessionIDstoredinacookienamedPHPSESSIDontheuser'sbrowser.2)ThisIDallowsPHPtoretrievesessiondatafromtheserver.

The security of PHP sessions can be achieved through the following measures: 1. Use session_regenerate_id() to regenerate the session ID when the user logs in or is an important operation. 2. Encrypt the transmission session ID through the HTTPS protocol. 3. Use session_save_path() to specify the secure directory to store session data and set permissions correctly.

PHPsessionfilesarestoredinthedirectoryspecifiedbysession.save_path,typically/tmponUnix-likesystemsorC:\Windows\TemponWindows.Tocustomizethis:1)Usesession_save_path()tosetacustomdirectory,ensuringit'swritable;2)Verifythecustomdirectoryexistsandiswrita


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