在PHP中保留键值对的同时扁平化数组

function flattenArray($array, $prefix = '') {
    $result = array();
    
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            $result = array_merge($result, flattenArray($value, $prefix . $key . '_'));
        } else {
            $result[$prefix . $key] = $value;
        }
    }
    
    return $result;
}

// 示例用法
$array = array(
    'name' => 'John',
    'age' => 25,
    'address' => array(
        'street' => '123 Main St',
        'city' => 'New York',
        'country' => 'USA'
    )
);

$flattenedArray = flattenArray($array);

print_r($flattenedArray);

Array
(
    [name] => John
    [age] => 25
    [address_street] => 123 Main St
    [address_city] => New York
    [address_country] => USA
)