how to use value from variable to if statement?

i have some problem with my code.

from a variable called :

$parameter = getDayName(date('w', $days)) == 'senin' || getDayName(date('w', $days)) == 'rabu';

to if statement like this :

if(getDayName(date('w', $days)) == 'senin' || getDayName(date('w', $days)) == 'rabu')
{
    echo ....
}
else
{
    echo...
}

the problem is can i use that variable in if statement like this:

if($parameter)
{
    echo ....
}
else
{
    echo...
}

because a variable parameter is always change

thank you for attention