- Exactly what are regex?
- Do we write them ourselves or are they prdefined expressions?
- If we can write regex ourselves, how do we write them?
- How do they check for invadalities?
For example the email regex:
[-0-9a-zA-Z.+_]+@[-0-9a-zA-Z.+_]+\.[a-zA-Z]{2,4}
how does this expression check for valid email addresses?
I have tried to look for simple explanations on the web but have found nothing confusing stuff.
Thankyou!