search
HomeBackend DevelopmentPHP TutorialPHP string interception function usage

PHP string interception function usage

Jul 17, 2017 am 09:20 AM
phpstringusage

The function that comes with PHP to intercept strings can only handle English. Numbers cannot intercept mixed Chinese characters. The latter example is easier to use. The first one is mainly for beginners to learn. The specific The code is as follows:

<?php 
  //构造字符串 
  $str = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 
  echo "原字符串:<b>".$str."</b><br>"; 
  //按各种方式进行截取 
  $str1 = substr($str,5); 
  echo "从第5个字符开始取至最后:".$str1."<br>"; 
  $str2 = substr($str,9,4); 
  echo "从第9个字符开始取4个字符:".$str2."<br>"; 
  $str3 = substr($str,-5); 
  echo "取倒数5个字符:".$str3."<br>"; 
  $str4 = substr($str,-8,4); 
  echo "从倒数第8个字符开始向后取4个字符:".$str4."<br>"; 
  $str5 = substr($str,-8,-2); 
  echo "从倒数第8个字符开始取到倒数第2个字符为止:".$str5."<br>"; 
 ?>

supports mixed Chinese and English interception, the code is as follows:

<?php 
/* 
------------------------------------------------------ 
参数: 
$str_cut    需要截断的字符串 
$length     允许字符串显示的最大长度 
 
程序功能:截取全角和半角(汉字和英文)混合的字符串以避免乱码 
------------------------------------------------------ 
*/ 
function substr_cut($str_cut,$length) 
{
    if (
strlen
($str_cut) > $length) 
    {  
        for($i=0; $i < $length; $i++)  
        if (ord($str_cut[$i]) > 128)    $i++;  
        $str_cut = substr($str_cut,0,$i)."..";  
    }  
    return $str_cut;  
} 
?>

The above is the detailed content of PHP string interception function usage. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
What data can be stored in a PHP session?What data can be stored in a PHP session?May 02, 2025 am 12:17 AM

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

How do you start a PHP session?How do you start a PHP session?May 02, 2025 am 12:16 AM

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

What is session regeneration, and how does it improve security?What is session regeneration, and how does it improve security?May 02, 2025 am 12:15 AM

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.

What are some performance considerations when using PHP sessions?What are some performance considerations when using PHP sessions?May 02, 2025 am 12:11 AM

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.

How do PHP sessions differ from cookies?How do PHP sessions differ from cookies?May 02, 2025 am 12:03 AM

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

How does PHP identify a user's session?How does PHP identify a user's session?May 01, 2025 am 12:23 AM

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

What are some best practices for securing PHP sessions?What are some best practices for securing PHP sessions?May 01, 2025 am 12:22 AM

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.

Where are PHP session files stored by default?Where are PHP session files stored by default?May 01, 2025 am 12:15 AM

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

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools