Regular Expression: +$ VS *$ VS none

Question

In regular expressions, what is the difference between ^[a-zA-Z]+$ and ^[a-zA-Z]*$. Also would I be able to not include it at all, either with ^[

Answer 1

^[a-zA-Z]+$

[a-zA-Z]+ match a single character present in the list below
Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
a-z a single character in the range between a and z (case sensitive)
A-Z a single character in the range between A and Z (case sensitive)
$ assert position at end of the string

So this will match basically any string of letters Foo, Bar, sdasndjkasnd
But will not match anything else like asds2, ab c, @23 Will not match

^[a-zA-Z]*S

[a-zA-Z]* match a single character present in the list below
Quantifier: * Between zero and unlimited times, as many times as possible, giving back as needed [greedy]
a-z a single character in the range between a and z (case sensitive)
A-Z a single character in the range between A and Z (case sensitive)
S matches the character S literally (case sensitive)

This will match the same but you MUST have a capital S at the end for a match.

Such as BallS, FooS, BarS will match -- ASzs will match [AS]
Balls, Foos Will not match though