php - Pass a variable within single quotes -

php - Pass a variable within single quotes -

could please educate me little on this? can't figure out how pass variable functions strftime.

for example:

$day = '%a'; echo strftime('$day', time());

i can't figure out how create variable not passed literal. help!

for example, don't need quotes @ all:

echo strftime($day, time());

php quotes strftime