Q: How to build file-name for File.WriteAllText dynamically with random number in it? I have numerous files and I want to write at a file randomly, what I want to do is this:
StringBuilder sb = new Stringbuilder(); 
int x;
Random rnd = new Random();

 x = rnd.Next(1,10);

File.WriteAllText("C:\\Top Folder\\File Folder\\file{0}.dat",x.ToString(),sb.ToString());

I know the argument on that WriteAllText is wrong, but that is the idea of what I want to do; Put whatever random number that is generated into {0} then write the contents of the Stringbuilder inside the file.
Help is much appreciated. Thanks in advance :D

A: You can use  String.Format:
string file = string.Format("C:\\Top Folder\\File Folder\\file{0}.dat", x);
File.WriteAllText(file, sb.ToString());

