Creating Diff Between Dates - general caster

Hi All,

Hoping someone can help.

I am looking to recreate this formula in general caster:

if(Today(), if({Last Emailed Date}, ROUNDUP(Days(Today(), {Last Emailed Date}), 0), “-”), “-”)

can someone help me with the syntax?

Ideally I’ll like to be able to work out the difference between a date column and todays date and cast this as a number column so I can then go on to send email triggers if the number is too small / large.

But I need to get the dates sorted first.

Thank you for your, help in advance.