String: replace last ".something" in a string?

Question

I have some string and I would like to replace the last .something with a new string. As example:

string replace = ".new";
blabla.test.bla.text.jpeg => blabla.test.bla.text.new
testfile_this.00001...csv => testfile_this.00001...new

So it doesn't matter how many ..... there are, I'd like to change only the last one and the string what after the last . is coming.

I saw in C# there is Path.ChangeExtension but its only working in a combination with a File - Is there no way to use this with a string only? Do I really need regex?

D'Arcy Rittich · Accepted Answer · 2012-07-25 13:26:53Z

4

string replace = ".new";
string p = "blabla.test.bla.text.jpeg";
Console.WriteLine(Path.GetFileNameWithoutExtension(p) + replace);

Output:

blabla.test.bla.text.new

answered Jul 25, 2012 at 13:26

D'Arcy Rittich

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Comments

Alex K. · Accepted Answer · 2012-07-25 13:29:40Z

4

ChangeExtension should work as advertised;

string replace = ".new";
string file = "testfile_this.00001...csv";

file = Path.ChangeExtension(file, replace);

>> testfile_this.00001...new

answered Jul 25, 2012 at 13:29

Alex K.

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1 Comment

miri Over a year ago

Huh, ChangeExtension for string only. Ok... didnt know ^^ Looks nice

Steve · Accepted Answer · 2012-07-25 14:05:46Z

4

You can use string.LastIndexOf('.');

string replace = ".new"; 
string test = "blabla.test.bla.text.jpeg";
int pos = test.LastIndexOf('.');
if(pos >= 0)
    string newString = test.Substring(0, pos-1) + replace;

of course some checking is required to be sure that LastIndexOf finds the final point.

However, seeing the other answers, let me say that, while Path.ChangeExtension works, it doesn't feel right to me to use a method from a operating system dependent file handling class to manipulate a string. (Of course, if this string is really a filename, then my objection is invalid)

edited Jul 25, 2012 at 14:05

answered Jul 25, 2012 at 13:26

Steve

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Comments

NominSim · Accepted Answer · 2012-07-25 13:27:37Z

1

string s = "blabla.test.bla.text.jpeg";
s = s.Substring(0, s.LastIndexOf(".")) + replace;

answered Jul 25, 2012 at 13:27

NominSim

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Comments

pyrocumulus · Accepted Answer · 2012-07-25 13:28:21Z

1

No you don't need regular expressions for this. Just .LastIndexOf and .Substring will suffice.

string replace = ".new";
string input = "blabla.bla.test.jpg";

string output = input.Substring(0, input.LastIndexOf('.')) + replace;
// output = "blabla.bla.test.new"

answered Jul 25, 2012 at 13:28

pyrocumulus

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Comments

lmcanavals · Accepted Answer · 2013-01-17 10:40:29Z

0

Please use this function.

public string ReplaceStirng(string originalSting, string replacedString)
{
    try
    {
        List<string> subString = originalSting.Split('.').ToList();
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < subString.Count - 1; i++)
        {
            stringBuilder.Append(subString[i]);
        }
        stringBuilder.Append(replacedString);
        return stringBuilder.ToString();
    }
    catch (Exception ex)
    {
        if (log.IsErrorEnabled)
            log.Error("[" + System.DateTime.Now.ToString() + "] " + System.Reflection.MethodBase.GetCurrentMethod().DeclaringType.FullName + " :: " + System.Reflection.MethodBase.GetCurrentMethod().Name + " :: ", ex);
            throw;
    }
}

edited Jan 17, 2013 at 10:40

lmcanavals

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answered Jul 25, 2012 at 13:36

Sachin

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