Problem with a regular expression...

Question

Anyone know why this is happening:

Filename:     031\_Lobby.jpg

RegExp:       (\d+)\_(.*)[^\_e|\_i]\.jpg

Replacement:  \1\_\2\_i.jpg

That produces this:

031\_Lobb\_i.jpg

For some reason it's chopping the last character from the second back- reference (the "y" in "Lobby". It doesn't do that when I remove the [^_e|_i] so I must be doing something wrong that's related to that.

Thanks!

Answer 1

You're forcing it to have a last character different from _e and _i. You should use this instead (note the last *):

(\d+)_(.*)[^_e|_i]*.jpg

Answer 2

You force it to chop off the last character with this part of your regex:

[^_e|_i]

Which translates as: Any single character except "_", "e", "|", "i".

The "y" in "Lobby" matches this criterion.

You mean "not _e" and "not _i", obviously, but that's not the way to express it. This would be right:

(\d+)_(.+)(?<!_[ei])\.jpg

Note that the dot needs to be escaped in regular expressions.

Answer 3

it is removing the "y" because [^_e|_i] matches the y, and the .* matches everything before the y.