Insert (single) spaces before and after a specific symbol

Question

I need to insert (single) spaces before and after a specific symbol (e.g. "|"), like this:

string input = "|ABC|xyz |123||999|   aaa|   |BBB";
string output = "| ABC | xyz | 123 | | 999 | aaa | | BBB";

This can easily be achieved using a couple of regular expression patterns:

string input = "|ABC|xyz |123||999|   aaa|   |BBB";

// add space before |
string pattern = "[a-zA-Z0-9\\s*]*\\|";
string replacement = "$0 ";
string output = Regex.Replace(input, pattern, replacement);

// add space after |
pattern = "\\|[a-zA-Z0-9\\s*]*";
replacement = " $0";
output = Regex.Replace(output, pattern, replacement);

// trim redundant spaces
pattern = "\\s+";
replacement = " ";
output = Regex.Replace(output, pattern, replacement).Trim();

Console.WriteLine("Original String: \"{0}\"", input);
Console.WriteLine("Replacement String: \"{0}\"", output);

But that is not what I want, my target is just use a single pattern.

I tried many ways but it still doesn't work as expected. Could anybody help me with this please.

Thank you so much in advance!

Define "doesn't work as expected". Do you get nothing back? The wrong result? An error? — Tim, Oct 05 '16 at 03:34
No error but wrong output result, for example there are more spaces than necessary (instead of 1 space), that's why I thought about combining a couple of patterns, but is it possible to use just a single pattern to achieve this? — Phong Ho, Oct 05 '16 at 03:41

score 4 · Answer 1 · answered Oct 08 '16 at 05:03

Thanks @Santhosh Nayak.

I just write more C# code to get the output as OP want.

string input = "|ABC|xyz |123||999|   aaa|   |BBB";
string pattern = @"[\s]*[|][\s]*";
string replacement = " | ";
string output = Regex.Replace(input, pattern, (match) => {
     if(match.Index != 0)
        return replacement;
     else
        return value;
});

I refer to Regex.Replace(string input, string pattern, MatchEvaluator evaluator) in MSDN.

score 0 · Answer 2 · answered Oct 05 '16 at 03:53

0

Try This.

string input = "|ABC|xyz |123||999|   aaa|   |BBB";

string pattern = @"[\s]*[|][\s]*";
string replacement = " | ";
string output = Regex.Replace(input, pattern, replacement);

answered Oct 05 '16 at 03:53

Santhosh Nayak

2,312
3
35
65

Thanks, but there are still redundant white spaces between `"|"`, output is `" | ABC | xyz | 123 | | 999 | aaa | | BBB"`. If there is no solution, perhaps I have to use one more pattern to remove redundant white spaces. – Phong Ho Oct 05 '16 at 04:14
@PhongHo I think you can use his regex pattern to get your result. We just write more Regex C# code :) . – cat916 Oct 08 '16 at 04:58

score 0 · Answer 3 · edited May 23 '17 at 10:34

Try this solution, based on this answer:

var str = "|ABC|xyz |123||999|   aaa|   |BBB";
var fixed = Regex.Replace(str, patt, m =>
            {
                if(string.IsNullOrWhiteSpace(m.Value))//multple spaces
                    return "";
                return " | ";
            });

This returns | ABC | xyz | 123 | | 999 | aaa | | BBB

We stil have |(space)(space)| between aaa and BBB but that is due to replacement of | with |.

Insert (single) spaces before and after a specific symbol

3 Answers3