CODEWITHSUNDEEP
c#stringsplit
user2706838
user2706838

Reputation: 1181

Best way to split string by last occurrence of character?

Let's say I need to split string like this:

Input string: "My. name. is Bond._James Bond!" Output 2 strings:

  1. "My. name. is Bond"
  2. "_James Bond!"

I tried this:

int lastDotIndex = inputString.LastIndexOf(".", System.StringComparison.Ordinal);
string firstPart = inputString.Remove(lastDotIndex);
string secondPart= inputString.Substring(lastDotIndex + 1, inputString.Length - firstPart.Length - 1);

Can someone propose more elegant way?

Upvotes: 96

Views: 109608

Answers (5)

wensveen
wensveen

Reputation: 884

A more concise version of Pierre-Luc's answer:

var s = "My. name. is Bond._James Bond!";

if (s.Split(".") is [.. var first, var last])
{
    Console.WriteLine(string.Join(".", first));
    Console.WriteLine(last);
}

The obvious drawback being the split-and-join with the same character for the first part. If you're only interested in the last part then you can use is [.., var last].

Upvotes: 0

Phil K
Phil K

Reputation: 5419

Updated Answer (for C# 8 and above)

C# 8 introduced a new feature called ranges and indices, which offer a more concise syntax for working with strings.

string s = "My. name. is Bond._James Bond!";
int idx = s.LastIndexOf('.');

if (idx != -1)
{
    Console.WriteLine(s[..idx]); // "My. name. is Bond"
    Console.WriteLine(s[(idx + 1)..]); // "_James Bond!"
}

Original Answer (for C# 7 and below)

This is the original answer that uses the string.Substring(int, int) method. It's still OK to use this method if you prefer.

string s = "My. name. is Bond._James Bond!";
int idx = s.LastIndexOf('.');

if (idx != -1)
{
    Console.WriteLine(s.Substring(0, idx)); // "My. name. is Bond"
    Console.WriteLine(s.Substring(idx + 1)); // "_James Bond!"
}

Upvotes: 196

Kevin
Kevin

Reputation: 4636

  1. Assuming you only want the split character to appear on the second and greater split strings...
  2. Assuming you want to ignore duplicate split characters...
  3. More curly braces... check...
  4. More elegant... maybe...

  5. More fun... Heck yeah!!

    var s = "My. name. is Bond._James Bond!";
var firstSplit = true;
var splitChar = '_';
var splitStrings = s.Split(new[] { splitChar }, StringSplitOptions.RemoveEmptyEntries)
    .Select(x =>
    {
        if (!firstSplit)
        {
            return splitChar + x;
        }
        firstSplit = false;
        return x;
    });

Upvotes: 3

Pierre-Luc Pineault
Pierre-Luc Pineault

Reputation: 9201

You can also use a little bit of LINQ. The first part is a little verbose, but the last part is pretty concise :

string input = "My. name. is Bond._James Bond!";

string[] split = input.Split('.');
string firstPart = string.Join(".", split.Take(split.Length - 1)); //My. name. is Bond
string lastPart = split.Last(); //_James Bond!

Upvotes: 16

rex
rex

Reputation: 3183

string[] theSplit = inputString.Split('_'); // split at underscore
string firstPart = theSplit[0]; // get the first part
string secondPart = "_" + theSplit[1]; // get the second part and concatenate the underscore to at the front

EDIT: Following from the comments; this only works if you have one instance of the underscore character in your input string.

Upvotes: 8

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