regex - PHP Check complicated String for correct format

Question

Looking for some help on how to validate a string in PHP.

The format to validate against is

X.XXam[d[i]-d[i] Only]

A sample entry could be:

8:55pm[Tues-Thurs Only]

d[i] represents an associative array value depending on the day of the week. For instance, the above contains Saturday and Sunday.

I need to make sure/validate this before inserting in the DB.

Can I get some help with this?

Answer 1

this should work for your case :

^d{1,2}:d{2}[ap]m[w+-w+ Only]$

demo here : http://regex101.com/r/mH9lX1