CODEWITHSUNDEEP
c#regexreplace
Ash
Ash

Reputation: 410

Replacing commas in a string with brackets and commas if they don't exist

I am trying to manipulate and clean up a string of database columns as follows.

Example Source string(s):

[foo],[bar],baz
[foo],bar,[baz]
[foo],[bar,[baz]
[foo],bar],[baz]
foo,bar,baz

(and so on)

Expected output:

[foo],[bar],[baz]

I have tried to run the following regex substitutions over the string:

        string columnString = "[foo],[bar],baz";

        if (!Regex.IsMatch(columnString, @"^\[.*"))
        {
            columnString = string.Concat("[", columnString);}
        if (!Regex.IsMatch(columnString, @"^.*\]$"))
        {
            columnString = string.Concat(columnString,"]");
        }
        while (!Regex.IsMatch(columnString, @"^.*\],.*$"))
        {
            columnString = Regex.Replace(columnString, @",", @"],");}
        while (!Regex.IsMatch(columnString, @"^.*,\[.*$"))
        {
            columnString = Regex.Replace(columnString, @"\],", @"],[");
        }

While this fixes up the leading and trailing brackets, it (obviously) doesn't deal with the commas where there is already an existing match in the string.

Can anyone suggest a method that would clean this up (it doesn't have to be regex).

Cheers

Upvotes: 1

Views: 464

Answers (3)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626802

I suggest a splitting and string rebuilding solution:

var result = string.Join(
    ",", 
    s.Split(',') // split with commas
        .Select(x => !x.StartsWith("[") && !x.EndsWith("]") ? $"[{x}]" : x ) // add [ ] to items not starting and ending with [ ]
);

See C# demo:

var strs = new List<string> { "[foo],[bar],baz", "[foo],bar,[baz]", "foo,bar,baz" };
foreach (var s in strs)
{
    var result = string.Join(",", s.Split(',').Select(x => !x.StartsWith("[") && !x.EndsWith("]") ? $"[{x}]" : x ));
    Console.WriteLine(result);
}

Output:

[foo],[bar],[baz]
[foo],[bar],[baz]
[foo],[bar],[baz]

Updated

As there may be items with either [ at the start or a ] at the end you may use

var result = string.Join(
    ",", 
    s.Split(',')
        .Select(x => !x.StartsWith("[") || !x.EndsWith("]") ? 
            $"[{Regex.Replace(x, @"^\[|]$", "")}]" : x 
    )
);

See this C# demo. Result:

[foo],[bar],[baz],[test]
[foo],[bar],[baz],[test]
[foo],[bar],[baz]

Note that Regex.Replace(x, @"^\[|]$", "") removes a [ at the start and ] at the end of the string.

Upvotes: 1

Robin Ding
Robin Ding

Reputation: 911

If you want to use regular expression, here is the answer:

var input = "[foo],bar,[baz]";
var regex = new Regex("((\\[?)((foo)|(bar)|(baz))(\\]?))");
var result = regex.Replace(input, "[$3]");

Please see: https://dotnetfiddle.net/Afnn3m

Upvotes: 0

Sarvesh Mishra
Sarvesh Mishra

Reputation: 2072

string str = "[foo],[bar],baz";
str = "[" + str.Replace("[", "").Replace("]", "").Replace(",", "],[") + "]";

Use StringBuilder if possible. I just gave you an idea using String class.

Upvotes: 1

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