Auto Incrementing file names in C#

Auto Incrementing file names in C#

I have a list of files like so
abc.txt
pas.txt
tempr.txt
What I would like to do is to append english alphabets to theese file
names .. the result should look like this
abc_a.txt
pas_b.txt
tempr_c.txt
This process should continue till the last character (i.e 'z'). if there
are more files then the file names would become
abc_a.txt
pas_b.txt
tempr_c.txt
.................
filename_z.txt
anotherfilename_a001.txt

Notice that the counter was again reset to the first character except an
integer was attached to it.
This is the code that i have right now. Please note that it is NOT working ..
string alphabets= "abcdefghijklmnopqrstuvwxyz";
List<string> filenames = new List<string>();
filenames.Add("test1.txt");
filenames.Add("newfile.cs");
filenames.Add("test2.txt");
filenames.Add("newfile2.cs");
string currentFileNmae = string.Empty;
foreach(string s in filenames) {
char usedAlphabet = new char();
for(int i = 0;i<=alphabets.Length-1;i+=11) {
usedAlphabet.Dump();
alphabets[i].Dump();
if(usedAlphabet != alphabets[i] )
{
if(currentFileNmae!= s)
{
string.Format("{0}--{1}",s,alphabets[i]).Dump();
usedAlphabet = alphabets[i];
currentFileNmae = s;
}
}
break;
}
}
I am part of a team that's building a file renamer tool for our internal
purposes and hence i need this code. This is part of the our enumertation
functionality that we have planned.
Please suggest. thanks