PHP函数从数组构建查询字符串

function build_query_string($array) {
    $query_string = '';
    foreach ($array as $key => $value) {
        $query_string .= $key . '=' . $value . '&';
    }
    return rtrim($query_string, '&');
}

$array = array(
    'name' => 'John',
    'age' => '30',
    'city' => 'New York'
);

$query_string = build_query_string($array);
echo $query_string; // 输出：name=John&age=30&city=New York