Regular expression to allow spaces between words
regex
Solution
tl;dr
Just add a space in your character class.
^[a-zA-Z0-9_ ]*$
Now, if you want to be strict...
The above isn't exactly correct. Due to the fact that `*` means zero or more, it would match all of the following cases that one would not usually mean to match:
- An empty string, "".
- A string comprised entirely of spaces, " ".
- A string that leads and / or trails with spaces, " Hello World ".
- A string that contains multiple spaces in between words, "Hello World".
Originally I didn't think such details were worth going into, as OP was asking such a basic question that it seemed strictness wasn't a concern. Now that the question's gained some popularity however, I want to say...
...use @stema's answer.
Which, in my flavor (without using `\w`) translates to:
^[a-zA-Z0-9_]+( [a-zA-Z0-9_]+)*$
(Please upvote @stema regardless.)
Some things to note about this (and @stema's) answer:
If you want to allow multiple spaces between words (say, if you'd like to allow accidental double-spaces, or if you're working with copy-pasted text from a PDF), then add a `+` after the space:
^\w+( +\w+)*$
If you want to allow tabs and newlines (whitespace characters), then replace the space with a `\s+`:
^\w+(\s+\w+)*$
Here I suggest the `+` by default because, for example, Windows linebreaks consist of two whitespace characters in sequence, `\r\n`, so you'll need the `+` to catch both.
Still not working?
Check what dialect of regular expressions you're using.* In languages like Java you'll have to escape your backslashes, i.e. `\\w` and `\\s`. In older or more basic languages and utilities, like `sed`, `\w` and `\s` aren't defined, so write them out with character classes, e.g. `[a-zA-Z0-9_]` and `[\f\n\p\r\t]`, respectively.
* I know this question is tagged vb.net, but based on 25,000+ views, I'm guessing it's not only those folks who are coming across this question. Currently it's the first hit on google for the search phrase, regular expression space word.
Problem
I want a regular expression that prevents symbols and only allows letters and numbers. The regex below works great, but it doesn't allow for spaces between words. ``` ^[a-zA-Z0-9_]*$ ``` For example, when using this regular expression "HelloWorld" is fine, but "Hello World" does not match. How can I tweak it to allow spaces?