Common PHP Utility Functions for String Handling, Encryption, and Validation

When starting PHP development, continuous learning is essential; this article shares a set of native utility functions that help beginners accelerate their coding practice.

1. msubstr – Truncate Chinese strings and append an ellipsis when the text is too long. This is useful when backend data exceeds the display space on the frontend.

/
/**
 * 截取中文字符串，过长的使用省略号代替
 */
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true){
    $str = preg_replace("/<a[^>]*>/i", "", $str);
    $str = preg_replace("/<\/a>/i", "", $str);
    $str = preg_replace("/<div[^>]*>/i", "", $str);
    $str = preg_replace("/<\/div>/i", "", $str);
    $str = preg_replace("/<!--[^>]*-->/i", "", $str);//注释内容
    $str = preg_replace("/style=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/class=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/id=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/lang=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/width=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/height=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/border=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/face=.+?['|\"]/i", "", $str);//去除样式
    $str = preg_replace("/face=.+?['|\"]/", "", $str);//去除样式只允许小写正则匹配没有带 i

    if(function_exists("mb_substr")){
        $slice = mb_substr($str, $start, $length, $charset);
    } elseif(function_exists('iconv_substr')) {
        $slice = iconv_substr($str, $start, $length, $charset);
    } else {
        preg_match_all($re[$charset], $str, $match);
        $slice = join("", array_slice($match[0], $start, $length));
    }
    $fix = '';
    if(strlen($slice) < strlen($str)){
        $fix = '...';
    }
    return $suffix ? $slice.$fix : $slice;
}

2. enctype – Optimized MD5 encryption with a configurable suffix. Useful for adding an extra layer of hashing to passwords.

/
/**
 * 公共方法
 * 优化md5加密：
 */
function enctype($password) {
    return md5($password . C('MD5_SUFFIX'));
}

3. suohao – Mask the middle four digits of a phone number with asterisks. Enhances privacy when displaying user phone numbers.

/
/**
 * 将手机号中间4位替换为*
 */
function suohao($phone){
    $p = substr($phone,0,3)."****".substr($phone,7,4);
    return $p;
}

4. isMobile – Validate mobile phone numbers using a regular expression. Ensures that submitted numbers conform to common Chinese mobile formats.

/
/**
 * 验证手机号是否正确
 * @author honfei
 * @param number $mobile
 */
function isMobile($mobile) {
    if (!is_numeric($mobile)) {
        return false;
    }
    return preg_match('#^13[\d]{9}$|^14[5,7]{1}\d{8}$|^15[^4]{1}\d{8}$|^17[0,6,7,8]{1}\d{8}$|^18[\d]{9}$#', $mobile) ? true : false;
}

5. isNumeric – Check whether a given input consists solely of digits. Helpful for validating numeric parameters.

/
/**
 * 验证输入的内容是否为纯数字
 * @author wdy
 * @param number $mobile
 */
function isNumeric($number) {
    if (!is_numeric($number)) {
        return false;
    }
    return preg_match('/^\d+$/i', $number) ? true : false;
}

6. isEmail – Validate email addresses with a regular expression. Used during user registration or email binding.

/
/**
 * 验证邮箱是否正确
 * @author wdy
 * @param [email protected] $email
 */
function isEmail($email){  
    $mode = '/\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/';  
    if(preg_match($mode,$email)){
        return true;
    }else{
        return false;
    }
}

7. recursive – Recursively reorder an infinite‑level category array, adding level and visual prefix. Suitable for e‑commerce category trees.

/
//递归重新排序无限极分类数组
function recursive($array,$pid=0,$level=0){
    //接收传递过来的数组
    $arr = array();
    foreach ($array as $value) {
        if($value['pid'] == $pid){
            //定义分类级别
            $value['level'] = $level;
            //定义分类分隔符号
            $value['html'] = str_repeat('-', $level);
            //$arr[]来存储$value
            $arr[] = $value;
            //array_merge()：函数把一个或多个数组合并为一个数组。
            $arr = array_merge($arr, recursive($array, $value['id'], $level+1));
        }
    }
    return $arr;
}

8. get_all_child – Retrieve IDs of all descendant categories recursively. Enables fast aggregation of sub‑category data.

/
//获取所有分类子分类的ID
function get_all_child($array, $id){
    //定义一个数组
    $arr = array();
    //循环遍历
    foreach ($array as $v) {
        //判断pid是否等于id
        if ($v['pid'] == $id) {
            // $arr接收所有的id
            $arr[] = $v['id'];
            //array_merge()：函数把一个或多个数组合并为一个数组。
            $arr = array_merge($arr, get_all_child($array, $v['id']));
        }
    }
    return $arr;
}

These functions can be directly integrated into PHP projects to streamline common backend operations such as text truncation, data masking, input validation, and hierarchical data processing.