Simple Regex: match everything until the last dot

Question

Just want to match every character up to but not including the last period

 dog.jpg     -> dog
 abc123.jpg.jpg -> abc123.jpg

I have tried

Answer 1

This will do the trick

(.*)\.

Regex Demo

The first captured group contains the name. You can access it as $1 or \1 as per your language

Answer 2

Regular expressions are greedy by default. This means that when a regex pattern is capable of matching more characters, it will match more characters.

This is a good thing, in your case. All you need to do is match characters and then a dot:

.*\.

That is,

.   # Match "any" character
*   # Do the previous thing (.) zero OR MORE times (any number of times)
\   # Escape the next character - treat it as a plain old character
.   # Escaped, just means "a dot".

So: being greedy by default, match any character AS MANY TIMES AS YOU CAN (because greedy) and then a literal dot.

Answer 3

Use lookahead to assert the last dot character:

.*(?=\.)

Live demo.