


PHP custom Chinese string interception function substr_for_gb2312 and substr_for_utf8 examples, _PHP tutorial
Examples of php custom Chinese string interception functions substr_for_gb2312 and substr_for_utf8,
This article describes the usage of php custom Chinese string interception functions substr_for_gb2312 and substr_for_utf8. Share it with everyone for your reference, the details are as follows:
/* *gb2312中文字符串截取 */ function substr_for_gb2312($str,$start,$len=null) { $totlelength = strlen($str); //特例情况 if ($len == null) $len = $totlelength; if ($len ==0) return ""; if ($len >= $totlelength && $start == 0 ) return $str; if ($start > $totlelength) return ""; //分析$start if ($start < 0 ) //$start<0时,转化为$start>0时的定位. { if ( abs($start) >= $totlelength ) $start = 0; else $start = $totlelength - abs($start); } //确定起始位置,当起始位拆分某汉字时,返回值包含此汉字. if ($start > 0) { $i = $start-1; $flag = -1; while ($i >= 0) { if ( ord(substr($str,$i,1)) > 160) { $flag = -1*$flag; } else break; $i--; } if($flag==1) { $start = $start - 1; $len++; //保证不位移. } } $str = substr($str,$start);//截除字符串$str的$start位前的字符 $totlelength = strlen($str); //确定结束位置,当结束位拆分某汉字时,返回值不包含此汉字. if ($len<0) $len = $totlelength - abs($len); if ($len <= 0) return ""; $i=min($len,$totlelength); $i--; $flag = -1; while ($i >= 0) { if (ord(substr($str,$i,1))>160) { $flag=-1*$flag; } else break; $i--; } if($flag == 1) $len=$len-1; $subit=substr($str,0,$len); return $subit; } /****************************************************************** * PHP截取UTF-8字符串,解决半字符问题。 * 英文、数字(半角)为1字节(8位),中文(全角)为3字节 * @return 取出的字符串, 当$len小于等于0时, 会返回整个字符串 * @param $str 源字符串 * $len 左边的子串的长度 ****************************************************************/ function substr_for_utf($str,$len) { for($i=0;$i<$len;$i++) { $temp_str=substr($str,0,1); if(ord($temp_str) > 127) { $i++; if($i<$len) { $new_str[]=substr($str,0,3); $str=substr($str,3); } } else { $new_str[]=substr($str,0,1); $str=substr($str,1); } } return join($new_str); } ?> /*带start位置的utf8截取函数*/ function utf8_substr($string, $start, $length) { preg_match_all ('/[/x00-/x7F]|[/xC2-/xDF][/x80-/xBF]|[/xE0-/xEF][/x80-/xBF][/x80-/xBF]|[/xF0-/xF4][/x80-/xBF][/x80-/xBF][/x80-/x BF]/', $string, $rs); $out = ''; $size = count ($rs[0]); $end = $start + $length; if ($end > $size ) { $end = $size; } for ($i = $start; $i < $end; $i++) { $out .= $rs[0][$i]; } return $out; }
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I hope this article will be helpful to everyone in PHP programming.

PHP is a server-side scripting language used for dynamic web development and server-side applications. 1.PHP is an interpreted language that does not require compilation and is suitable for rapid development. 2. PHP code is embedded in HTML, making it easy to develop web pages. 3. PHP processes server-side logic, generates HTML output, and supports user interaction and data processing. 4. PHP can interact with the database, process form submission, and execute server-side tasks.

PHP has shaped the network over the past few decades and will continue to play an important role in web development. 1) PHP originated in 1994 and has become the first choice for developers due to its ease of use and seamless integration with MySQL. 2) Its core functions include generating dynamic content and integrating with the database, allowing the website to be updated in real time and displayed in personalized manner. 3) The wide application and ecosystem of PHP have driven its long-term impact, but it also faces version updates and security challenges. 4) Performance improvements in recent years, such as the release of PHP7, enable it to compete with modern languages. 5) In the future, PHP needs to deal with new challenges such as containerization and microservices, but its flexibility and active community make it adaptable.

The core benefits of PHP include ease of learning, strong web development support, rich libraries and frameworks, high performance and scalability, cross-platform compatibility, and cost-effectiveness. 1) Easy to learn and use, suitable for beginners; 2) Good integration with web servers and supports multiple databases; 3) Have powerful frameworks such as Laravel; 4) High performance can be achieved through optimization; 5) Support multiple operating systems; 6) Open source to reduce development costs.

PHP is not dead. 1) The PHP community actively solves performance and security issues, and PHP7.x improves performance. 2) PHP is suitable for modern web development and is widely used in large websites. 3) PHP is easy to learn and the server performs well, but the type system is not as strict as static languages. 4) PHP is still important in the fields of content management and e-commerce, and the ecosystem continues to evolve. 5) Optimize performance through OPcache and APC, and use OOP and design patterns to improve code quality.

PHP and Python have their own advantages and disadvantages, and the choice depends on the project requirements. 1) PHP is suitable for web development, easy to learn, rich community resources, but the syntax is not modern enough, and performance and security need to be paid attention to. 2) Python is suitable for data science and machine learning, with concise syntax and easy to learn, but there are bottlenecks in execution speed and memory management.

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.


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