How to insert/replace string value into another string value at certain place? - string

Question

This is an uploading tool. I am trying to rename a file name if it is existed in the folder already.
The plan is to add a number after the file name. For example, if the file name is Hello.doc, it will be saved as Hello2.doc.
The problem is, the file name & file type are always different. It can be Goodbye.pdf/capture.png. I am not sure how to insert the number in the correct place.
if (System.IO.File.Exists(savepath))
{
int counter = 2;
while (System.IO.File.Exists(savepath))
{
string newFileName = fileName + counter;
tempFileName = newFileName.Insert/replace //Not sure what to do here
savepath += tempFileName;
counter++;
}
FileUpload.SaveAs(savepath);
lblUpload.Text = "A file with the same name already exists." + " Your file was saved as " + tempFileName;
}
Does someone know? Thanks!

Answer 1

Please let me know if this is what you were looking for. Used StringBuilder to avoid creating new String objects after every concatenation.
String[] filepath = filename.split(".");
// filepath[0] -> filename
// filepath[1] -> extension
StringBuilder newFilename = new StringBuilder(filepath[0]);
// add number
newFilename.append(2);
// add period
newFilename.append(".");
// add extension
newFilename.append(filepath[1]);
return newFilename.toString();