I want to distinguish php flag to set based on current working hosting...

In htaccess I'm using this

<if "%{HTTP_HOST} == 'localhost' ">
    # PHP error handling for development servers
    php_flag display_startup_errors on
    php_flag display_errors on
    .......
</if>
<Elseif "%{HTTP_HOST} == 'mywebsite.com' ">
    .......
</Elseif>

How to do the same with user.ini ?