Replace all occurrences of a white space from string except the first occurrence using Regex in C#

Question

The input string having multiple whitespaces, and the result should have only one white space left, other whitespaces must be replaced with string.Empty

Input String: +1 580 5691 234 or (435) 772-5992

Output String: +1 5805691234 or +1 4357725992

Regex.Replace(text, @"[^\d]", string.Empty) replaces all the whitespaces.

Try `(?<!^\S*)\D` or `(?<!^\+?\d*)\D`. Please add either a set of more or less comprehensive test cases, or exact pattern requirements. — Wiktor Stribiżew, Jan 04 '18 at 12:08
This fails for the Input : (435) 772-5992 , Special Chars must also be removed — CodeConstruct, Jan 04 '18 at 12:10
So, `435 7725992` is the expected output for the string above? — Wiktor Stribiżew, Jan 04 '18 at 12:15
Actually no, for the type of string (435) 772-5992 i add +1 at the start, then it should be like +1 4357725992, but input string is (435) 772-5992. I have to handle both scenarios with a single regex. — CodeConstruct, Jan 04 '18 at 12:24
What's your actual requirement? Is the goal to take any phone number and end up with: "+1 ######"? Will you ALWAYS have "+1 " in the output string? — aquinas, Jan 04 '18 at 12:34
Yes! and it has been achieved by modifying your given regex to this "(?<!\+^?\d*)\D". Thanks a lot — CodeConstruct, Jan 04 '18 at 12:37
How about (at least) a comment to us spending time trying to come up with an answer for you. And if you found another solution, an explanation of how you solved it. — SamWhan, Jan 18 '18 at 09:22

score 0 · Answer 1 · answered Jan 04 '18 at 12:37

0

You don't have to do it all within one line:

Remove the special characters as you like, get the position of the first space, remove spaces with your regex only in the substring after the first space.

answered Jan 04 '18 at 12:37

Matheus Lacerda

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SamWhan · Answer 2 · 2018-01-05T10:29:00.653

If you absolutely must do it with a single regex, this might be a solution for you:

Replace

^(?:\+1)?\D*(\d*)?\D*(\d*)?\D*(\d*)?\D*(\d*)?\D*(\d*)?$

with

+1 $1$2$3$4$5

Using 5 separate capture groups, it captures only digits, possibly separated by non-digits. If there are less than 5 digit groups, they're simply ignored.

Note that the optional preceding country code isn't captured either, and that the replace string always inserts it (back, if it existed).

This specific example limits the number of digit groups to 5, but could easily be expanded.

Here at regexstorm.net.

and illustrated here at regex101.

score 0 · Answer 3 · answered Jan 04 '18 at 16:13

The .NET Regex engine can manage this with a lookbehind:

(?<=\s+.*)\s+

It matches all blocks of whitespace which are preceded by at least one block of whitespace followed by some non-whitespace characters.

Using it as Regex.Replace(text, "(?<=\s+.*)\s+", string.Empty) on the string +1 580 5691 234 produces the output +1 5805691234.

Replace all occurrences of a white space from string except the first occurrence using Regex in C#

3 Answers3