Blank spaces in regular expression

Question

I use this regular to validate many of the input fields of my java web app:

"^[a-zA-Z0-9]+$"

But i need to modify it, because i have a couple of fields that need to allow blank spaces(for example: Address).

How can i modify it to allow blank spaces(if possible not at the start).

I think i need to use some scape character like \

I tried a few different combinations but none of them worked. Can somebody help me with this regex?

I did it: This is the pattern i used: `^([a-zA-Z0-9]+[a-zA-Z0-9 ]+$)?` At the end i use ? when the fields needs to be optional. Thanks for your answers. — javing, Apr 22 '11 at 09:28

darioo · Accepted Answer · 2011-04-22T08:04:07.390

7

I'd suggest using this:

^[a-zA-Z0-9][a-zA-Z0-9 ]+$

It adds two things: first, you're guaranteed not to have a space at the beginning, while allowing characters you need. Afterwards, letters a-z and A-Z are allowed, as well as all digits and spaces (there's a space at the end of my regex).

edited Apr 22 '11 at 08:04

answered Apr 22 '11 at 07:26

darioo

46,442
10
75
103

This allows _any_ char (other than a space) as the first char, (e.g. any of these: `@&^$@*&^$#)(@#*$`) Probably not what you want! – ridgerunner Apr 22 '11 at 07:47
@ridgerunner: you're correct; I updated my answer. I'd say this is the most readable version for use – darioo Apr 22 '11 at 08:04

score 3 · Answer 2 · answered Apr 22 '11 at 07:28

If you want to use only a whitespace, you can do:

^[a-zA-Z0-9 ]+$

If you want to include tabs \t, new-line \n \r\n characters, you can do:

^[a-zA-Z0-9\s]+$

Also, as you asked, if you don't want the whitespace to be at the begining:

^[a-zA-Z0-9][a-zA-Z0-9 ]+$

score 2 · Answer 3 · answered Apr 22 '11 at 07:25

2

Use this: ^[a-zA-Z0-9]+[a-zA-Z0-9 ]+$. This should work. First atom ensures that there must be at least one character at beginning.

answered Apr 22 '11 at 07:25

Arnab Das

3,548
8
31
43

the first `+` is unnecessary. – Oscar Mederos Apr 22 '11 at 07:28
@Oskar Yep. You are right. So the right one is `^[a-zA-Z0-9][a-zA-Z0-9 ]+$`. I think darioo's regex is more compact. – Arnab Das Apr 22 '11 at 07:40

score 1 · Answer 4 · edited Apr 22 '11 at 07:23

1

try like this ^[a-zA-Z0-9 ]+$ that is, add a space in it

edited Apr 22 '11 at 07:23

pavium

14,808
4
33
50

answered Apr 22 '11 at 07:21

Mahesh KP

6,248
13
50
71

for to start with a character try like this ^[a-zA-Z0-9][a-zA-Z0-9 ]+$ – Mahesh KP Apr 22 '11 at 07:27

score 1 · Answer 5 · answered Apr 22 '11 at 07:41

1

This regex dont allow spaces at the end of string, one downside it accepts underscore character also.

^(\w+ )+\w+|\w+$

answered Apr 22 '11 at 07:41

Gursel Koca

20,940
2
24
34

score 1 · Answer 6 · answered Apr 22 '11 at 07:51

Try this one: I assume that any input with a length of at least one character is valid. The previously mentioned answers does not take that into account.

"^[a-zA-Z0-9][a-zA-Z0-9 ]*$"

If you want to allow all whitespace characters, replace the space by "\s"

Blank spaces in regular expression

6 Answers6

Linked