php下划线与驼峰互转

/**
 * 下划线转驼峰
 *
 * @param string $string    原字符
 * @param string $separator 分隔符
 *
 * @return string
 */
function camelCase(string $string, string $separator = '_')
{
    $string = $separator . str_replace($separator, ' ', strtolower($string));
    return str_replace(' ', '', ucwords(ltrim($string, $separator)));
}

/**
 * 驼峰转下划线
 *
 * @param string $camelCaps
 * @param string $separator
 *
 * @return string
 */
function unCamelCase(string $camelCaps, string $separator = '_')
{
    return strtolower(preg_replace('/([a-z])([A-Z])/', "$1" . $separator . "$2", $camelCaps));
}