[Solved] Why does a*ad$ match the string “ad”? [duplicate]

Question

Shouldn’t the a* match with the a in the string?

No, because * means a can match zero or more times, so the '' empty string also matches that expression. That leaves 'ad' after the initial empty string to match for the remainder of the expression.

A regex will consider both options here (both '', the empty string, and 'a' satisfy the a* pattern).

Use a+ if you wanted the pattern to match at least once.

Accepted Answer

Shouldn’t the a* match with the a in the string?

No, because * means a can match zero or more times, so the '' empty string also matches that expression. That leaves 'ad' after the initial empty string to match for the remainder of the expression.

A regex will consider both options here (both '', the empty string, and 'a' satisfy the a* pattern).

Use a+ if you wanted the pattern to match at least once.