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20 個實用 PHP 程式碼片段：字串、陣列、檔案、圖片、驗證與工具函式精選

編輯：PHP 相關知識

前言

整理 20 個高頻使用的 PHP 片段，涵蓋隨機字串、郵件驗證、目錄操作、JSON/XML 解析、Slug 生成、真實 IP 取得、強制下載、標籤雲、相似度比對、Gravatar、斷詞截斷、ZIP 壓縮解壓、URL 處理、超連結轉換、圖片縮圖、AJAX 偵測等，適合收藏備查。

1. 可閱讀隨機字串（子音+母音交替）

function readable_random_string($length = 6) {
    $conso = ['b','c','d','f','g','h','j','k','l','m','n','p','r','s','t','v','w','x','y','z'];
    $vocal = ['a','e','i','o','u'];
    $password = '';
    for ($i = 0; $i < $length/2; $i++) {
        $password .= $conso[array_rand($conso)] . $vocal[array_rand($vocal)];
    }
    return $password;
}

2. 純隨機字串（含大小寫字母數字）

function generate_rand($len) {
    $chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    $rand = '';
    for ($i = 0; $i < $len; $i++) $rand .= $chars[random_int(0, strlen($chars)-1)];
    return $rand;
}

3. Email 地址編碼防採集（JS 輸出）

function encode_email($email='info@domain.com', $linkText='Contact Us', $attrs='class="emailencoder"') {
    $email = str_replace(['@','.'], ['@','.'], $email);
    $linkText = str_replace(['@','.'], ['@','.'], $linkText);
    $parts = ['',''];
    $encoded = '';
    return $encoded;
}

4. Email 格式 + MX 記錄雙重驗證

function is_valid_email($email, $check_mx = false) {
    if (!preg_match('/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,})$/i', $email))
        return false;
    if ($check_mx) {
        list(, $domain) = explode('@', $email);
        return checkdnsrr($domain, 'MX');
    }
    return true;
}

5. 列出目錄內容（排除 . .. Thumbs.db）

function list_files($dir) {
    if (is_dir($dir) && $handle = opendir($dir)) {
        while (false !== ($file = readdir($handle))) {
            if (!in_array($file, ['.','..','Thumbs.db']))
                echo "{$file}
\n";
        }
        closedir($handle);
    }
}

6. 遞迴刪除目錄（含檔案）

function destroyDir($dir, $virtual = false) {
    $ds = DIRECTORY_SEPARATOR;
    $dir = $virtual ? realpath($dir) : $dir;
    $dir = rtrim($dir, $ds);
    if (is_dir($dir) && $handle = opendir($dir)) {
        while (($file = readdir($handle)) !== false) {
            if (in_array($file, ['.','..'])) continue;
            $path = $dir . $ds . $file;
            is_dir($path) ? destroyDir($path) : unlink($path);
        }
        closedir($handle);
        return rmdir($dir);
    }
    return false;
}

7. JSON 解析

$json = '{"id":1,"name":"foo","email":"foo@foobar.com","interest":["wordpress","php"]}';
$obj = json_decode($json);
echo $obj->name;           // foo
echo $obj->interest[1];    // php

8. XML 解析 (SimpleXML)

$xml = simplexml_load_string($xml_string);
foreach ($xml->user as $user) {
    echo $user['id'] . ' ' . $user->name . ' ' . $user->email . '
';
}

9. 生成 URL 友善 Slug

function create_slug($string) {
    return preg_replace('/[^A-Za-z0-9-]+/', '-', $string);
}

10. 取得用戶真實 IP（支援代理）

function getRealIpAddr() {
    if (!empty($_SERVER['HTTP_CLIENT_IP'])) return $_SERVER['HTTP_CLIENT_IP'];
    if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) return $_SERVER['HTTP_X_FORWARDED_FOR'];
    return $_SERVER['REMOTE_ADDR'];
}

11. 強制檔案下載

function force_download($file) {
    if (isset($file) && file_exists($file)) {
        header('Content-Length: ' . filesize($file));
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename="' . basename($file) . '"');
        readfile($file);
    } else { echo 'No file selected'; }
}

12. 標籤雲生成（字體大小對應計數）

function getCloud($data=[], $min=12, $max=30) {
    $minC = min(array_values($data)); $maxC = max(array_values($data));
    $spread = $maxC - $minC ?: 1;
    $tags = [];
    foreach ($data as $tag => $count) {
        $size = $min + ($count - $minC) * ($max - $min) / $spread;
        $tags[] = ''.htmlspecialchars($tag).'';
    }
    return join("\n", $tags);
}
// 用法
$arr = ['Actionscript'=>35,'Adobe'=>22,'Array'=>44,'Background'=>43];
echo getCloud($arr, 12, 36);

13. 字串相似度比較

similar_text($str1, $str2, $percent);
echo $percent; // 相似百分比

14. Gravatar 通用頭像

function show_gravatar($email, $size=80, $default='', $rating='G') {
    echo '';
}

15. 斷詞截斷（保留完整單詞）

function myTruncate($string, $limit, $break=' ', $pad='...') {
    if (strlen($string) <= $limit) return $string;
    if (false !== ($bp = strpos($string, $break, $limit))) {
        if ($bp < strlen($string)-1) $string = substr($string,0,$bp).$pad;
    }
    return $string;
}

16. 建立 ZIP 壓縮檔

function create_zip($files=[], $dest='', $overwrite=false) {
    if (file_exists($dest) && !$overwrite) return false;
    $valid = array_filter($files, 'file_exists');
    if (!$valid) return false;
    $zip = new ZipArchive();
    if ($zip->open($dest, $overwrite ? ZipArchive::OVERWRITE : ZipArchive::CREATE) !== true) return false;
    foreach ($valid as $file) $zip->addFile($file, basename($file));
    $zip->close();
    return file_exists($dest);
}
// 用法
create_zip(['file1.jpg','file2.jpg'], 'backup.zip', true);

17. 解壓 ZIP 檔

function unzip_file($file, $dest) {
    $zip = new ZipArchive();
    if ($zip->open($file) !== true) die('Could not open archive');
    $zip->extractTo($dest);
    $zip->close();
    echo 'Archive extracted to '.$dest;
}

18. URL 自動補全 https://

if (!preg_match('/^(http|ftp):/i', $_POST['url'])) {
    $_POST['url'] = 'https://'.$_POST['url'];
}

19. 文字中的 URL/Email 自動轉超連結

function makeClickableLinks($text) {
    $text = preg_replace('/((f|ht)tp:\/\/[-a-zA-Z0-9@:%_+.~#?&\/=]+)/i', '$1', $text);
    $text = preg_replace('/([\s(\[{])(www\.[-a-zA-Z0-9@:%_+.~#?&\/=]+)/i', '$1$2', $text);
    $text = preg_replace('/([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,3})/i', '$1', $text);
    return $text;
}

20. 圖片縮圖（等比縮放）

function resize_image($filename, $tmpname, $xmax, $ymax) {
    $ext = strtolower(pathinfo($filename, PATHINFO_EXTENSION));
    $im = match($ext) {
        'jpg','jpeg' => imagecreatefromjpeg($tmpname),
        'png' => imagecreatefrompng($tmpname),
        'gif' => imagecreatefromgif($tmpname),
        default => false
    };
    if (!$im) return false;
    $x = imagesx($im); $y = imagesy($im);
    if ($x <= $xmax && $y <= $ymax) return $im;
    if ($x >= $y) { $newx = $xmax; $newy = $y * $xmax / $x; }
    else { $newy = $ymax; $newx = $x * $ymax / $y; }
    $im2 = imagecreatetruecolor($newx, $newy);
    imagecopyresampled($im2, $im, 0,0,0,0, $newx, $newy, $x, $y);
    return $im2;
}

21. 偵測 AJAX 請求

if (!empty($_SERVER['HTTP_X_REQUESTED_WITH']) &&
    strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) === 'xmlhttprequest') {
    // AJAX 請求
} else {
    // 一般請求
}