Regular Expression

[gulumal]

I have a regular expression.

"^.?$"

According to documentation "." is any character except \n
? is zero or one times preceding character.

string "a" matches.
"aa" does not match. Should "aa" match?
"ab" does not match. Should it match?

Can an guru explain me this please?


thx
gulumal

[boudino]

"aa" does not match. Should "aa" match?
"ab" does not match. Should it match?

No, it shouldn't because of ^ and $ in regular expressionm, which means begin and end of line including and the expression is evaluated as a whole. Your expression means begin-zero or just one chars-ends, but in these samples, the pattern is begin-first char-second char-end, which doesn't match, because the end of line is expected after max one char, not two.