Regex to match filename containing a word, regardless of case

regex

23,385

Solution 1

Like @Sebastian P mentioned:

/^.*icon.*\.png$/i

Except I'm adding the i flag to the end to mark it as case-insensitive.

Solution 2

If you only need to verify filenames, this should do the trick:

Pattern regex = Pattern.compile("^.*icon.*\\.png$", Pattern.CASE_INSENSITIVE);

If you get paths also, and want to extract the filename, use this:

Pattern regex = Pattern.compile("(?<=^|[\\\\/])([^\\\\/]*icon[^\\\\/]*\\.png)$", Pattern.CASE_INSENSITIVE);

To explain this one: I use negated character classes for \ and / to ensure that everything is part of the filename, and then I ensure that we go until the start of the filename with a lookbehind.

tzippy

Updated on July 05, 2022

Comments

tzippy almost 2 years
I need a regex that matches any filename of the type .png containing the word icon in all its cases. So it should match
```
icon.png
myicon.png
thisIcon.PnG
aniCon_this.png
ANYICON.PNG
[email protected]
```
Any help appreciated!! Thanks! PS: I'm in java
Sebastian Paaske Tørholm about 13 years

It would, but then C:\icons\panda.png would match, too.
tchrist about 13 years

@Sebaastin: So? That was the requirement.
Sebastian Paaske Tørholm about 13 years

@tchrist: If you re-read the requirements, it should match any filename that contains icon and ends in .png. If the path is C:\icons\panda.png, the filename does not contain icon, the path does.
tchrist about 13 years

@Sebastian: If the open(2) syscall accepts it, it is clearly a filename. The presence or absense of directory separators is a matter to be left to namei(9) to resolve for you, and has no bearing on whether you have a legal filename or not. That means that "/" is just as much of a filename as "." or ".." or "......." or "foo" or "foo/foo" or "/foo/foo/foo.foo.foo/../foofoo/..foo" is.
Brad Christie about 13 years

@SebastianP, Though I'm sure the extra-mile is appreciated, there was no indication the original input would include a filepath, only a filename. ;-)
tchrist about 13 years

@Brad: "filename", "pathname", and "path" are wholly synonymous. See your local kernel. A "file" is of course different from a "filename", being related to the underlying inode rather than the path to reach it. But there is no sense of "file path" that is different from "filename" or "pathname".
Sebastian Paaske Tørholm about 13 years

@tchrist: Now you're nitpicking. When people say filename, they usually mean the name given to a file. Most people wouldn't consider moving a file to another directory renaming the file. That said, if that's what he desires, he can just use the first regex, as it works for that case, as well.
tzippy about 13 years

I have to agree with Sebastian. Thanks for the input and the discussion. But if I had the same definition for "filename" like you, @tchrist I would not ask a question about such a simple regex ;)
tchrist about 13 years

@Sebastian: To rename => rename - change the name of a file on BSD, Solaris, and MacOS. All those accept rename("/abc/xyz","/def/xyz") which changes its path. To change its path is to change its name. Filename and pathname have no separate meaning. Perhaps you are confusing basename. Not system programmers, eh?
tchrist about 13 years

@Sebastian: Your pattern fails on filenames with any of the Java newline sequences in them. Mine doesn’t.