Php从数组创建正确的字符串

<?php
$array = array('Hello', 'World', '!');
$string = implode(' ', $array);
echo $string;
?>

Hello World !

<?php
$array = array('Hello', 'World', array('This', 'is', 'a', 'nested', 'array'));
$string = recursiveImplode(' ', $array);

function recursiveImplode($glue, $array) {
    $result = '';

    foreach ($array as $value) {
        if (is_array($value)) {
            $result .= recursiveImplode($glue, $value) . $glue;
        } else {
            $result .= $value . $glue;
        }
    }

    return rtrim($result, $glue);
}

echo $string;
?>

Hello World This is a nested array