php extension check and load

<?php
/**
 *列出所有加载的扩展及其包含的函数
 */
$exts = get_loaded_extensions();
foreach ($exts as $ext) {
    $funs = get_extension_funcs($ext);
    echo "当前扩展名称:" . $ext . "及其包含的函数<br>";
    foreach ($funs as $fun) {
        echo "<li>$fun</li>";
    }
}
// Example loading an extension based on OS  
if (!extension_loaded(&#39;sqlite&#39;)) {
    if (strtoupper(substr(PHP_OS, 0, 3)) === &#39;WIN&#39;) {
        dl(&#39;php_sqlite.dll&#39;);
    } else {
        dl(&#39;sqlite.so&#39;);
    }
}
// Or, the PHP_SHLIB_SUFFIX constant is available as of PHP 4.3.0  
if (!extension_loaded(&#39;sqlite&#39;)) {
    $prefix = (PHP_SHLIB_SUFFIX === &#39;dll&#39;) ? &#39;php_&#39; : &#39;&#39;;
    dl($prefix . &#39;sqlite.&#39; . PHP_SHLIB_SUFFIX);
}
?>