Regular expression for patterns in CodeIgniter URIs

Question

I have another question asked her on Stack Overflow and was suggested to use regular expressions instead of PHP code. Unfortunately I don’t know regexp, and have tried many times in the past and now to understand it without success. So hopefully, if I ask nicely, someone here could help. I would be very grateful.

What I’m trying to achieve is so route different URI requests to different places, 4 to be specific. What would be a proper reg exp to match the following:

• year (example: 2010)
• year-month (example: 2010-nov) (the month represented by 3 chars)
• year-month-day (example: 2010-nov-10)
• year-month-day-string (example: 2010-nov-10-blog-post-title-here)

I’m coding in PHP and using the CodeIgniter framework.

Regards, Jason

Answer 1

Since you are validating later. you can go really generic:

([0-9]{4})-([a-z]{3})-([0-9]{1,2})-([\w*](-?[\w*])*)

4 digits year, a hyphen, a 3 char lowercase word, a hyphen, two digits, at least one word, (optional hyphen and another word repeated as needed.)

Answer 2

• Year is (19|20)\d\d.

• Year-month is (19|20)\d\d\-[a-z]{3}

• Year-month-day is (19|20)\d\d\-[a-z]{3}\-[1-3][0-9]

• Year-month-day-string is (19|20)\d\d\-[a-z]{3}\-[1-3][0-9]\-[a-z\-]*

Correct me if I'm wrong, please. Also note that there is no validation for month names or dates that don't really exist.